1)This guide is meant to give an in-depth description of a particular way to play Sivir.
2)This build is for 5v5.
3)This build primarily focuses on a mid-lane Sivir.
4)Even if this sounds like a crazy build to you, at least try it once or twice before down-voting.
5)Any constructive criticism will be greatly appreciated.
6)Do not simply down-vote because you think Sivir is a bad champion.
7)This is my first build guide, so I borrowed a variety of styles from other guides.

The beautiful and deadly champion known as Sivir has been a favorite of League summoners for close to a decade. A soldier-for-hire outside of the Fields of Justice, she is the embodiment of a highly successful mercenary on modern day Runeterra. Sivir has little interest in the ''cribbage sheets'' - as she calls them - of League influence bartering. Instead, she is motivated by material wealth and riches, and she is paid handsomely for her services. Sivir is one of the wealthiest individuals found anywhere on Valoran. Sivir owns multiple residences in a number of different city-states, as well as ownership stakes in a number of businesses all across Valoran. Her detractors, either envious of her success or acrimonious of her flexible morality, have begun to use Sivir as a symbol of what is wrong with the mercenary nature of the League. Sivir dismisses her critics, saying that while her personal code of ethics is less ruthless than her competitors, ''Everyone has a price.''

Sivir has earned many titles and accolades throughout her illustrious career, but the one she held until recently was ''Battle Mistress of Noxus''. Now she is simply known as ''The Battle Mistress'' after breaking her contract with the Noxian High Command. Sivir dared to object to the Noxian war against the peaceful island state of Ionia, though less about the morality of the issue than the planning behind it; her predictions of a bloody stalemate came true when the Ionians held off the relentless assaults of the Noxians. Claiming that the Noxian High Command had lost its direction, she left Noxus and made her services available to the Institute of War. The Noxian High Command has sent a number of contracted assassins to deal with its rogue mercenary, but none have delivered her or survived.

''Time and time again, Sivir proves that she has earned the right to call herself 'The Battle Mistress'.'' -- Jax

Welcome to my Sivir build. Sivir is the first champion I bought when I started to play league of legends and since then I have continued playing her as my primary champion. I have worked my way through a variety of different item, rune, and mastery builds in the process. This guide can be helpful to those who have never used Sivir before, as well as those of you who like me use her very often. If at any time, you notice anything missing from my guide, or change because of a recent update, please let me know. I hope you have fun reading and enjoy this guide. If you do please up-vote. I hope to see Sivir being played more consistently in future League of Legends matches. I have made a few slight modifications to my build and am now re-posting it. The primary reason for me re-posting my build is because my old Sivir guide received troll votes and rage votes from people who did not like me commenting on their builds.

Damage: 52.11 (+2.9 / per level)
Attack Speed: 0.679 (+3.1%/ per level
Range: 425
Health: 378 (+82 / per level)
Mana: 203 (+43 / per level)
Move Speed: 310
Armor: 12.75 (+3.3 / per level)
Magic Resist: 30 (+0 / per level)
Health Regen: 4.25 (+0.55 / per level)
Mana Regen: 4 (+0.3 / per level)

Greater Mark Of Desolation-This is arguably a must have for any high DPS champion. Armor Penetration is very helpful early game when your attack damage is still very low. Armor Pen is also very nice later in the game when you are facing champions with very high armor such as Malphite or Rammus. With runes focusing on armor penetration, as well as the very high attack damage per hit provided by my item build, even tanks can be taken down fairly quickly.

Greater Seal of Evasion-Due to somewhat recent updates to items in League of Legends, there are currently very few items that provide dodge chance. Sivir already has a dodge chance through her passive if she is moving. Therefore, with the additional 6.75% dodge chance provided through runes, late in the game Sivir has a 31.75% dodge chance while moving. As I will get into later in my guide, this should be most of the time.

Greater Glyph of Cooldown Reduction-Cooldown reduction on any champion is a good thing. The more reduction you have the more often you can use your spells. Having flat cooldown reduction allows you to use your Spell Shield more frequently early game, and the difference between flat and per lvl is not extremely significant. This also allows you to have Boomerang Blade up more often, but you do not want to spam this ability or you will run out of mana and push your lane rather than simply last hit.

Greater Quintessence Of Desolation-The same reason as I gave for Greater Mark Of Desolation. With Marks and Quintessences focused on armor pen, without any items, you begin the game with significant additional damage per attack. This is helpful for harassing and clearing out minions quickly if needed.

For my masteries, I choose to put 21 into Utility and the remaining into Defense.
Spatial Accuracy and Blink of an Eye to improve your summoner spells
Perseverance because extra regen is always nice
Awareness to reach level 18 faster
Meditation for a slight increase in mana regen
Utility Mastery to extend how long Lizard Buff will last
Quickness for some extra movement speed
Intelligence because cooldown reduction is always nice
Presence of the master so you can use Teleport and Ghost more often
Evasion to work alongside your passive
Nimbleness because you will be dodging fairly often

Flash-This is simply the best or one of the best spells in the game currently for anyone. It can save your life countless times in a game, as well as help you to run down an enemy that escapes around a corner. Flash also helps you to get out of the center of attention if you are being focused. It is just a great all around spell and should always be one of your two spells on Sivir

Teleport-This is one of the most valuable summoner spells in my opinion on many champions. Furthermore, it is almost essential to have at least one on a team. As Sivir, if you are going to be midding; in most cases you can easily recall, buy items, and Teleport back to your turret before the enemy mid is able to touch it. This is also a very helpful spell for back-dooring with or without minion support. If minions are pushing down a lane solo and everyone else is occupied, you can Teleport over and kill the turret before the other team can do anything. Also if you did not use your Teleport to get to the turret, you can use it immediately afterwards to rejoin your team. This is better than recall in some cases because damage does not prevent you from using Teleport unless you die. Finally, with Sivir's great ability to wipe out minion waves and hold off a tower until support arrives, Teleport can get you there in seconds.

Ghost-For Sivir Ghost is a great multi-purpose spell. If you choose not to use Teleport you still need a way to get around the map so fast you can use Ghost instead. I currently prefer teleport for the ability to be two places on opposite sides of the map in seconds. However, if you need to get away after destroying a tower, Ghost and On The Hunt should make you uncatchable. Also, sometimes in team-fights, it can just be helpful to not have to worry about running around anyone. If you get Ghost instead of Teleport remember to adjust your masteries.

Fleet of Foot-At maximum level, Sivir's passive provides her with an additional 25% dodge chance while moving. This is one of the reasons why Sivir should be consistently moving in team fights. This passive is also very helpful when you are running back to safety after destroying an enemy turret because all of their basic attacks have a higher chance of being dodged.

Boomerang Blade-EARLY GAME HARASSMENT! If you use this wisely in the early game, especially if you are doing solo mid, your opponent will quickly learn to stay behind his minions and avoid engaging. One of the biggest mistakes I see with people playing Sivir is that they use Boomerang Blade to try to kill minions too early on. This is just a waste of mana. Any time that you have Boomerang Blade available you should be looking for an opportunity to hit the enemy champion directly. This ability is also very useful when you are pushed up to the opponents turret. While they are there killing your minions; simply run up, throw your Boomerang Blade and run back before the turret can focus you. I do not start using Boomerang Blade to clear out minion waves until I have a b.f. sword in most cases unless they are up to your turret of course.
Late game, Boomerang Blade has a few different uses. The first thing to make note of is the fact that this ability does magic damage, as do most abilities. In a team fight, you should be consistently throwing in Boomerang Blade or waiting for its cooldown. This is a very good way to greatly damage or kill the enemies squishy targets without having to come very close to the battle. This can also be very effective in attacking champions who only have armor, but very little magic resist. Often, I will throw my boomerang blade at the tanks later on in a fight after the squishies have been taken care of.

Ricochet-This is a way to harass your opponents without even trying early game. Just make sure you do not drain yourself of mana doing this. This is also the ability that will allow you to wipe out an entire team simultaneously late game. I have gotten penta-kills simply from basic attacking with Ricochet on and maybe one Boomerang Blade. Some people emphasize the importance of stacking attack speed on Sivir because of Ricochet. The problem with this is that Ricochet costs mana per hit and the higher your attack speed early game, the faster your mana will be drained.

Spell Shield-This is the ability that sets excellent Sivir players apart from all the rest. You will notice in my skill sequence that I take one level of Spell Shield before leveling up everything else. The reason for this is that the only difference between levels is the length of the cooldown, which is nice to bring down, but leveling up the other abilities is more important. This ability is extremely important in the laning phase. FREE MANA! Many people tend to overlook this aspect of spell shield; both those who play Sivir and those who play against Sivir. Spell Shield costs 75 mana, but if it blocks an ability, you then restore 125 mana. This is the primary way that I keep my mana up early game. This ability also works great in conjunction with Boomerang Blade. When you see an enemy champion coming towards you to use an ability, you immediately activate Spell Shield and then throw Boomerang Blade. This not only negates the ability the enemy champion just attempted to use, but often the enemy champion is committed to the point where they get hit by the Boomerang Blade going both ways. The other way that Spell Shield is huge early game is in the situation of being ganked. I hardly ever get ganked, even if I am pushing all the way up to the enemies turret. As soon as you see the ganking enemy champion coming into your lane, immediately activate Spell Shield and run to your turret throwing Boomerang Blade in the process. This also greatly discourages future ganking attempts, and I have also gotten several kills because the enemy attempting to gank over-commits.
All of these applications of Spell Shield are fairly simple and automatic. (If "blank" happens, respond with "blank.") Late game is where you will have to spend time getting used to when exactly you should activate Spell Shield. A good basic rule is that if you are about to run into a fight you activate spell shield. Other than this, you have to recognize when a champion has actually committed to using an ability on you and react very quickly. Otherwise you will just activate Spell Shield to early; in which case, the enemy will simply wait until it runs out and then attack you while it is on cooldown.


On The Hunt-My description for this ability is much more simple than for the above abilities. Three main uses: any large team fight, immediately activate On The Hunt; if you are backdooring and attacking a turret while everyone else is occupied, activate On The Hunt; and if you see a few of your allied champions are trying to escape a fight with enemies close behind them, activate On The Hunt, run up to your teammates, and run back with them.

Note:Other obvious uses for On The Hunt are if you are fighting Baron and possibly if you are soloing Dragon.

After watching a number of different high skill players streams and testing it out on my own many times I have come to realize that it is very much worth it to stack a few doran's blades early and you still can get late game items just as easily. This also gives you a boost early game while the other mid is saving up for bigger items. It is also good to be able to return to base often and then come right back so that you can harass consistently while you are in-lane knowing how much you need to preserve your mana before you will be returning for the next item. It allows you to be more generous with harassment, but still you cannot overdo it. I start with just a Doran's Blade obvious because that costs the full amount. I then stay in lane until I can buy the second Doran's Blade and Boots. Then recall to base and teleport back or if you have killed the enemy mid you can go to help another lane first and then teleport to mid before the enemy mid can attack it. After this I try to save up for both Berserker's Greaves and the third Doran's Blade, but if you need to go help people out and you can only buy the greaves the next trip back that is okay. Furthermore, some games I will not buy the third doran's blade before a B. F. Sword. This happens when I need to stay in lane longer and I end up getting close to 1650 before I am close to needing to go back.

Note:If you are going 1v2 you will want too start with a different item set, which is explained in the chapter on 1v2.

Note:These items require you to be a bit more careful with mana than mana regen items, but they also allow help to increase your early game damage output.

Note:If you realize that you are dominating your lane and having no trouble farming and keeping the advantage than you will likely want to bypass the third and maybe the second Doran's Blade to by the B. F. Sword sooner.

More Early Game Damage=Lane Dominance=Free Farm
After you get the B. F. Sword you must make a decision between Bloodthirster and Infinity Edge. You will eventually get both of these items and possibly two of Bloodthirster. If you are losing very little health still and you want a quick boost to damage and some nice crits then you will go for the Infinity Edge. However, if you are being harassed or losing a lot of health in team fights then you will go for Bloodthirster. This does not give as much immediate damage, but eventually it builds up to 100 and a very significant amount of lifesteal. After getting one of these items, not both you will want to get Zeke's Harbinger because it is very likely that you are already having more teamfights than solo fights so auras are the way to go. This item gives very nice attack speed and lifesteal. It also lowers the armor of all enemy champions, which is great for everybody. After this I will usually go for the other option between Infinity Edge and Bloodthirster.

Note:If the laning phase ends very early and you are struggling with mages early you can grab the Negatron Cloak or Banshee's Veil earlier.
Berserker's Greaves-This build does not focus very heavily on attack speed, but more so on damage so the attack speed boost from boots is very helpful.

Bloodthirster-This is where the game starts to take off very quickly. Thanks to Sivir's ability to take out entire creep waves with one Boomerang Blade, you can quickly rack up the additional 40 attack damage, and 10% lifesteal.

Infinity Edge-This was even a good option before the buff and then they gave it some additional damage so now it is even better. The critical chance percentage may not seem extremely significant on this item, but look at it this way. It adds 80 damage. For easy math I will calculate in a 25% critical chance. This means that for every 4 attacks on average your damage would be 80+80+80+200=440. Therefore, this item alone actually gives closer to 110 attack damage, but then the 250% boost to damage also gets applied to all of your other damage as well. This item is nigh essential on any physical dps champion.

Zeke's Harbinger-Attack speed + Lifesteal + Armor Reduction + Aura = Scary Carry. This item is just a great item and it is a must in almost every game for one of the physical dps characters. It helps everybody on your team and hurts everybody on their team. Oh, plus it has a little passive health regen as well just thrown in there. Buy this item if noone else on your team has. You should be the one buying the item, but make sure you don't buy it along with another teammate. Not worth it two have double auras because only you and the other person that bought it can benefit from both. One of you could have a better item in the spot.

Banshee's Veil-Banshee's veil is another core item in this build. It gives you a nice little bonus in health as well as mana, which is nice because you do not want to have to rely on any other mana sources. It also gives magic resist, which is key and finally the most important reason is that if you can get good at using your Spell Shield in conjunction with the Banshee's Veil, you can quickly block two enemy spells. It is important to note that Banshee's Veil pops BEFORE Spell Shield.

Note:The very significant damage boost and lifesteal provided by Bloodthirster makes it a core item of this build and probably my favorite item in the game. Boomerang Blade now gains additional damage based upon (1.00)x(Bonus attack damage). Furthermore, a reason I focus on attack damage is because attack damage is the most significant stat that affects Ricochet and the only stat that affects Boomerang Blade except magic penetration, but who buys that on a [hysical dps character.. Any on-hit effects only apply to the first target hit. On The Hunt alone provides Sivir and her teammates with a significant attack speed boost.

Bloodthirster-If you are having no trouble with enemy AD champions and your Banshee's Veil has proven to be significant enough to save you from nearing death from their magic damage, bring on the extra damage. With this second Bloodthirster you would now have 70% lifesteal. Once you have an Infinity Edge, this item is the most significant way that you can build up your attack damage and survivability through attacking. It's a great option and I get it in the majority of my games.

Black Cleaver-If you are having no issues with survivability, but you want to be able to kill those squishies a little faster or break through that tanks shell. This is the item for you. After the third hit, the champion you are targeting will start to see their health go down very quickly. This item also gives some more attack speed, which is always nice.

Last Whisper-So the other team is starting to hate you...a lot and now they are all building armor to counter your ridiculous damage output. Toss in this item and just laugh as they see 40% of their precious armor that they have built up fade away. I would only get this item if you see the enemy team as a whole starting to build significant armor or if their tank has a ton of armor.

Guardian Angel-This is a very good option for the last item in a different scenario. If you are having very little issue with ad champions, but they are doing a ton of magic damage. This item will still give you a little armor, along with a nice chunk of magic resist. Finally, the passive, means a very very bad day for the opposing team. You do a ton of damage and they are finally able to take you out, now the rest of your team is working on cleaning up and possibly struggling a bit so the enemy is dumb enough to stick around. Suddenly, you are back again and with your massive attack damage, you can be back to full health in a few attacks.

Note:If the enemy team has a ton of CC and you are still being CC'd a lot even with your double spell shields than you might want to trade your Berserker's Greaves for Mercury's Treads at some point.

Note:If both teams are in a stalemate and you need to focus on backdooring primarily you might want to swap our Berserker's Greaves for Mobility Boots.

Some people include elixirs at various parts throughout their build for specific purposes. However, with using Sivir I would only suggested buying elixirs once you have finished your primary build (a.k.a the six items you want to end the game with). Once you have these six items, as soon as you have more than 750 gold and get an opportunity to return to base you want to buy elixirs. Buy Elixir of Fortitude, Elixir of Agility, and Elixir of Brilliance. You only need to buy an Oracle's Elixir if the other team has stealthed champions. If you are going to buy an Oracle's Elixir in this first batch, you will instead need 1150 gold. Many people underestimate elixirs. There have been multiple times where in very long games, elixirs gave just enough boost to give our team an edge.

Note:Continue to buy new elixirs if yours run out and the game is not over yet.

Note:You only need to buy an Oracle's Elixir once if you can stay alive.

Early Game

During the early game, I usually take on a slightly defensive play-style. However, since you will be returning to base fairly often for items and mana refill you can feel free to harass and chip away at the other champion. With the lifesteal from the doran's blades stacking up you can get your health back quick enough that you need not be afraid to harass the other champion some and get hurt a little yourself. Otherwise, the enemy champion will have too much opportunity to free farm. By playing this way, I am usually able to either force the enemy champion out of lane multiple times without having to return myself, force the enemy champion to turret hug getting gold deprived, or rack up a couple kills when they underestimate the damage of Boomerang Blade.
I do not worry about hitting the turret myself unless the enemy mid leaves to try to interfere with a side lane. If you have On The Hunt, and a wave a minions; you should be able to do some serious damage or maybe even destroy the first mid-lane turret if the enemy champion is foolish enough to leave you alone mid to help out with a side-lane. You always want to recall to base as soon as possible once you have 825 gold to buy Boots and another Doran's Blade. I usually find that I have enough gold to return to base and purchase the next set of items by the time my Teleport is ready or soon after.
I spend the majority of the laning phase between my turret and the middle of the lane. By doing this, the only way for the enemy champion to come out and get minion kills without getting attacked by the minions is to come within range of Boomerang Blade.

Note:If this is still not working for you and you are having to play extremely defensive, do not be afraid to use boomerang blade once in a while simply for last hits. Simply, you need to farm!

Note:At early levels, you mainly only want to use Ricochet when it will get you an extra last hit or when they are at your turret. Otherwise, you will probably run low on mana.

Mid Game

Once I have my first main damaging item or at least the B. F. Sword, I play more offensively in order to push over the middle turret if I haven't already. At this point I begin to run to other lanes and usually my team is able to push over the side turrets without much trouble because of the 3 people in the lane and the fact that I can harass the enemy champions if they try to stop us from attacking the turret. However, I only go to other lanes to help out if my Teleport is on cooldown, or if the minions are pretty close to the second middle turret. All the while, I am farming as many minions as possible, including those in the jungle. I also usually try to grab the Lizard buff unless my team has a very possessive jungler.

Note:Sometimes you have to go to help out with other lanes simply because your teammates are having trouble holding their lane. Do not be afraid to leave your turret lonely if you can score a couple kills and/or save some teammates.

Late Game

If the game has actually lasted this long, after you have gold deprived their mid who likely should be their carry, this is when Sivir gets extremely fun to play. At this point you will already have at Bloodthirster and/or Infinity Edge as well as Zeke's Harbinger. With these three items, you build up some very significant DPS. I have found that most of the time when I play, my teammates do not really feel like running back and forth between lanes to push back encroaching minions waves. I am perfectly fine with taking this job. Sivir can easily dispact 20 or more minions with one Boomerang Blade and a few attacks with Ricochet bouncing all around. What this means for you is that you will reach level 18 very soon, and you will also be able to finish your build soon.

Team Fight

There are a variety of different ways that games play out once you get past the 40-45 minute mark. Sometimes there are just pretty consistent team fights. For these it is important to understand your role. This is where you having to be very active and make good use of your spell shield. If you are able to wait a second or so after the team fight start before activating On The Hunt and joining, this is ideal. Focus on the squishies with your Boomerang Blade and basic attacks, and let your Ricochet handle the rest. This is especially important if you are fighting a Rammus with Defensive Ball Curl or anyone with Thornmail. As long as you do not directly attack the champions with these items, you can damage them with your Ricochet without taking any damage from the effects. Once all of the squishies have been taken care of, you can then easily take on these champions head on.

Back-dooring

The possible option is for you to begin back-dooring, which is something that Sivir excels in over most other champions. Usually I choose to back-door with minion support, which some do not consider back-dooring, but you are still attacking the enemy on you own from a different direction than that which they are focused on. If you have noticed that both teams have just been pushing back and forth slightly in one lane without doing much, and your team is having no trouble staying alive playing defensively. This is a prime time for you to break away and push down a side lane to a turret. If nothing else, this will draw away one or two of the character from the other team, and then your team suddenly has a slight edge. However, there are also times when you team will just yell at you if you are back-dooring when you are needed elsewhere.

Note:Your teammates may expect you to be in charge of warding Baron and Dragon because you will probably make the most gold on your team. Whether you have to do it or someone else on your team does, it is very important to keep Baron and Dragon warded.

Note:Once you have your first Bloodthirster, you can solo Dragon, but you will need the help of On The Hunt. Once you get your second Bloodthirster you can solo Dragon without any problems. Keep this in mind and try to kill Dragon as soon as he re-spawns if possible. This is great for everyone on your team.

Note:If you are running away, you are probably still slowly losing health to those chasing you and attacking. If you are fighting you actually have a chance, especially if you are now close to 75% lifesteal. There are times for flight and times to fight. Also remember that you can use your ultimate simply to escape and it will be worth it because of the short cooldown.

This chapter is by request and I am very thankful for the suggestion. If you react quickly and appropriately with Sivir you should never have to fear being ganked mid. If you see that two or more enemy champions are MIA excluding the jungler then be smart and play defensive. If you pay attention to when people are recalling and when enemies die then you will also have a better idea of why certain champions are not on the map. If there are only two or less champions MIA including the jungler, continue to to hold the fight around the middle of the lane.

The Gank

As soon as you see another enemy champion come into your lane, most likely from one of the side bushes or from near your turret, activate your spell shield and run you your turret. I always try to throw a Boomerang Blade at the ganking party as well to deter them. Most champions will initiate with an ability that is meant to hold you in place so that they and their teammate can have some free hits and kill you. If you can block this first ability then you have a very good chance of escape. For example, if Amumu comes flying in with Bandage Toss and you block it and just keep running, you have a very good chance of escaping plus, that mean ganker that came to ruin your party gets a Boomerang Blade to the face. Depending on how much damage you are able to do with the Boomerang Blade you may even be able to turn around and kill the champion who attempted to gank you are the other mid who ran out for some free attacks. Additionally, do not forget that you can use Ghost or On The Hunt to get to safety faster if necessary, but do not waste it.

Akali-Despite her being melee, she will sometimes take mid if there is not a better mid on the team. She is very easy for Sivir to take care of. Simply Spell Shield her Mark of the Assassin and out-push her, throwing your Boomerang Blade when you see an opening even if she goes into her Twilight Shroud.

Anivia-Due to a recent update, it now costs significantly more for Anivia to quickly turn her Glacial Storm on and off in order to kill a minion wave. Because of this, you should have no problem keeping the fight near the middle of the lane. Her Flash Frost is very easy to Spell Shield because it comes at you very slowly.

Annie-The main thing to focus on with Annie is her ability to stun you. Pay attention to when she has reached the point where her next spell will stun. You can see a small swirl around her. This is not to be confused with Molten Shield, which is an orange bubble around her. Be sure to activate Spell Shield if you see Disintegrate coming towards you. It is very important to harass her with Boomerang Blade consistently so that she cannot just sit back and farm.

Ashe-I hardly ever come close to running out of mana when I face an Ashe. When she fires her Volley, it is very easy to activate Spell Shield and situate yourself to get hit by one of the arrows. If you see her fire Enchanted Crystal Arrow, try to warn your teammates.

Caitlyn-I have found this champion to be the most difficult for me to counter as Sivir. She can very easily out-range you so that it is difficult to go in for last hits. Try to stay pretty close to your turret most of the time and use Spell Shield whenever she fires Piltover Peacemaker. however, you need to stay far enough away that she cannot shoot your turret with her long range. Once you get your first Bloodthirster, if you are still in the laning phase, she will not be much of a problem. If you need free mana, activate Spell Shield and run over her Yordle Snap Trap.

Cassiopeia-You want to prevent her from being able to effect both you and your minions simultaneously with her aoe poison, so this means usually staying a few steps away from your minions. Cassiopeia is one of the most frail champions early on so harassing her with
Boomerang Blade can quickly force hher to be defensive.

Corki-It is very easy to Spell Shield both Missile Barrage and Phosphorus Bomb. Anytime he uses Gatling Gun, just back away until it runs out. Corki has a pretty long range, so he can definitely out-range Sivir with basic attacks.

Ezreal-I usually play fairly defensively here. Ezreal can quickly jump to you with
Arcane Shift and follow it up with his other abilities. If this happens you have to be very quick to activate Spell Shield. Similar to if you are facing Ashe, warn teammates if you see him fire Trueshot Barrage.

Fiddlesticks- Reap can be very dangerous because it will prevent you from using your Spell Shield or Boomerang Blade if you get hit. If you get silenced, simply back up a few steps until it goes away. When you see Fiddlesticks using Bountiful Harvest, throw in your Boomerang Blade and it might be enough for him to cut it off early.

Galio-I have only played against a Galio mid once or twice. Just keep in mind that he can slow you with Resolute Smite, as well as speed himself up with Righteous Gust, to chase you down very quickly. If you are able to Spell Shield Resolute Smite, this becomes a non-issue.

Heimerdinger-If you play smart, you are able to take out his H-28G Evolution Turret without putting yourself in any danger simply with Ricochet. Also, do not be afraid to focus directly on his H-28G Evolution Turret with your Boomerang Blade. It is worth the mana to take these turrets out quickly, and sometimes Heimerdinger will even stand right next to them, so you damage them both significantly. Save your Spell Shield for any time you see his ch-1 concussion grenade coming toward you.

Karma-At this point, I have not played any games against Karma mid so this will be updated once I have first-hand experience. One pointer is to avoid over-committing when she is low health, because Soul Shield provides a significant shield and she can also slow you under her turret with Spirit Bond.

Karthus-If you are having trouble with avoiding his Lay Waste, stay close to your minions because it does significantly less damage when it hits multiple targets. Also, you can consistently regain mana by activating Spell Shield on top of Lay Waste. Most importantly, you can completely negate his Requiem against you with Spell Shield. Warn your team when Karthus reaches level 6 so that they know he can use Requiem now.

Kassadin-At level one, you should play very defensively because in most cases Kassadin takes Null Sphere at level one. There is nothing you can do against this and it hurts a lot, so if you let yourself get hit a few times you may have to recall early. Once you hit level two, it becomes very easy to activate Spell Shield to make Null Sphere useless. Once Kassadin hits level 6, Riftwalk just gets annoying. You have to have very fast reflexes to see when he is about to Riftwalk and back up quickly and use Spell Shield if you have it.

Katarina-This is another melee champion that make take mid. Play defensively so that most of the fighting is near your turret and use Spell Shield and time you see her Bouncing Blades bouncing toward you. You do not have to worry about her hitting your turret much at all even with a full wave of minions there because you can throw Boomerang Blade to hurt her and scare her away. Never underestimate Death Lotus. Remember you are frail.

Kennen-In most cases, very frail at least in the early game. Your Boomerang Blade will take a large chunk of his health each hit. When Kennen uses Lightning Rush I usually run back a few steps so that he chases and then activate Spell Shield before running into him and firing off a point black Boomerang Blade and a couple basic attacks. When he uses Slicing Maelstrom, just get out fast.

Kog'Maw-Focus on last hitting and keeping the fight near the middle. Once Kog'Maw reaches level 6 you will have to start dodging Living Artillery fairly often. When Spell Shield is available, use it. When it is not, move around a lot.

LeBlanc-The main danger here is Distortion. Usually she will return to her original position before you can do much damage to her, but activate Spell Shield when you see her about to use Distortion. If you are able to fire off a Boomerang Blade, there is a possibility of hitting her an additional time.

Lux-Focus on last hitting and playing defensively. Spell Shield any time you are in her Lucent Singularity, as well as if you will be one of the two targets hit by Light Binding. Usually, by staying behind minions, this is not an issue.

Malzahar-Unless you can get the upper hand early, you will probably be near your turret most of the time until you get B. F. Sword. Stay away from any minions afflicted by Malefic Visions because it could jump to you. Call of the Void allows for plenty of time to activate Spell Shield so just hold onto Spell Shield until he uses Call of the Void.

Miss Fortune-She can clear out minions very quickly with Make it Rain. Just stay out of the circle and hit her with Boomerang Blade if you get a chance. After Make it Rain ends, then move in and kill the minion wave. You may be near your turret often against Miss Fortune.

Mordekaiser-I have had to mid against Mordekaiser a fair number of times and Iron Man is just annoying. Consistently harass him to keep his shield low or empty. This also forces him to use other spells to refill it such as, Mace of Spades or Siphon of Destruction, which you can use Spell Shield on to regain mana.

Morgana-Always get out of Tormented Shadow as soon as possible. Morgana will often use Dark Binding follwed by Tormented Shadow if you are without minion support under your turret. Quickly use Spell Shield to avoid the snare and then you can just walk out of Tormented Shadow. This also causes her to waste mana. Do not waste your mana by throwing Boomerang Blade when she is using Black Shield if possible.

Nidalee-She is rarely in mid, but when she is she can be annoying. Javelin Toss deals more damage the farther away you are, so if you are very far away it hurts a lot. This is what you want to focus on with Spell Shield. Javelin Toss moves very slowly so it is easy to see coming. I rarely see her use Aspect Of The Cougar in mid to come after a champion.

Pantheon-The combination of Aegis of Zeonia and Heartseeker Strike is very dangerous. As long as you activate Spell Shield before Aegis of Zeonia, you can quickly move out of Heartseeker Strike and also hit Pantheon with a Boomerang Blade. Otherwise, just farm away and harass him consistently.

Ryze-I have only played a few games against the new Ryze, but I have actually found him to be easier to deal with early game. When you see Spell Flux bouncing around, you can activate your Spell Shield if there aren't many minions and most likely you will get some free mana. Just be careful with getting caught to far out with his Rune Prison.

Sivir-The most annoying thing in my opinion, is to lane against another Sivir. Keep in mind that she can dodge your first swipe of Boomerang Blade and run back into it with Spell Shield for free mana just like you can. Therefore, you have to judge the reflexes of the other Sivir and be very accurate when you choose to throw Boomerang Blade. Try to avoid her Ricochet bouncing around. If you get stuck under your turret without minion support, be very careful about her Boomerang Blade.

Swain-One of his best abilities Nevermove can be made pretty useless if you can react quickly with Spell Shield. This is his best ability in my opinion, so if you are able to prevent him from rooting you, you can play pretty offensively. Be careful when Swain uses Ravenous Flock, but do not be scared away. I usually cause him to actually lose health by the end of Ravenous Flock with Boomerang Blade.

Teemo- Boomerang Blade takes away a huge chunk of Teemo's health right away. you can last hit pretty easily because Teemo only has 500 range, which is less than most other ranged characters, but it is still higher than Sivir. Any time you see Blinding Dart coming, use Spell Shield. If you see Teemo "use" camouflage and go invisible, throw your Boomerang Blade directly at him. It is usually good to invest in an Oracle's Elixir if you are midding against a Teemo because you will see him when he is invisible, and your Ricochet will kill his Noxious Traps.

Tristana-Her range can be a significant problem because it starts at 550 and continues to increase each level. Luckily, with Ricochet you are able to still compete with her range with the bounces. It is very important to use Spell Shield when she uses Rocket Jump or Explosive Shot. You need to work hard to harass her with Boomerang Blade or she can just farm freely.

Twisted Fate-Luckily you can use Spell Shield to block Pick A Card, especially if he uses gold card. However, Pick A Card has a very low cool-down so you have to be defensive. If Twisted Fate stops using Pick A Card on you because you keep using Spell Shield, you still have an opportunity of regaining your mana by allowing yourself to get hit by Wild Cards. Warn your teammates when Twisted Fate reaches level 6 so that they know she can use Destiny now.

Twitch-An Oracle's Elixir is almost necessary if you are mid-lane against a Twitch. Otherwise, he can move around behind you and kill you before you even get close to your turret. You will want to play very defensively regardless, because Deadly Venom makes his basic attacks very dangerous. The good thing is that Twitch is very very frail.

Urgot-Avoid getting hit by his basic attacks because with his passive Zaun-Touched Bolt Augmenter they cause you to do less damage. The good news is that you are finally against a ranged character with a smaller range than you. Focus on avoiding Noxian Corrosive Charge with your Spell Shield. Be careful not to get extremely close to his turret because he can use his Hyper-Kinetic Position Reverser to switch places with you and put you under or behind his turret. Focus on killing minions and avoiding his Noxian Corrosive Charge. He may block the damage from Boomerang Blade sometimes with Terror Capacitor, which provides him with a shield.

Veigar-Extremely frail! At level nine, if you hit him with your Boomerang Blade going both ways, it will most likely take him below half health. Veigar should focus on last hitting minions with Baleful Strike in order to build up his AP, which allows you to farm freely. Once he gets to level 6, be careful of Primordial Burst, which does a significant amount of damage even at low levels.

Vladimir-Thanks to a recent update in League of Legends, Vladimir is somewhat less dangerous. Most of the time he will learn to avoid using Transfusion on you because of your Spell Shield and will start to focus on minions, but if not enjoy the steady mana. Vladimir is fairly easy to harass with Boomerang Blade and Ricochet because his range is the same as yours (450).

Zilean-He has a long range and his Time Bombs are annoying. Most Zileans will quickly learn to avoid placing their Time Bomb on you and will place it on the minion right next to you so that you cannot use Spell Shield to block it and you still receive damage. Personally, I recommend still using Spell Shield when you see him about to place a Time Bomb just to be safe unless you are having significant mana problems. Zilean has low maximum health, so it is important to harass him as often as you can with Boomerang Blade. Because of his Time Bomb and long range, you might be under your own turret most of the time, but this is fine because he does very little damage to it.

Note:This does not address every champion in every situation, but it covers the majority.

I follow the same skill sequence and starting items for 2v2 as I use for 1v1. I start by buying my items and trying to get to the tower as quickly as possible. Walk fairly close to the bush and line up your Boomerang Blade so that it travels almost the whole length of the first bush. After you throw your blade, you can tell if it hits anybody because it will make a quick noise and there will be a small visual hint as well. If you notice it hit anyone, warn your other lane-mate, and decide if you want to go in or stay away. You have to pay attention to who is on the other team when you are doing this. For example, if you notice that the other team has a Blitzcrank, obviously it would be a bad idea to get very close to the bushes when throwing your Boomerang Blade because then he can just pull you in, which often equals a dead Sivir. If you get to your lane fast enough, you will be back to full mana before the minions even arrive. I rarely go into the second set of bushes on the enemies half of the lane.

Just as if you were mid-lane 1v1, you want to harass the enemy champions consistently. Depending on the enemy champions and how squishy they are, sometimes I will focus primarily on just hitting the one with my Boomerang Blade or alternating between the two so that they are both low health. If you notice that one of them is good at dodging your Boomerang Blade while the other is not, just go for the easy target. You want to be getting as many last hits as possible and hope that you are laning with a champion that is not extremely gold dependent. All champions need gold, but some do much better than others with less gold. You need gold early to shine mid-late game.

Any time that you want to go for one of the enemy champions; ping, message, or at least do something to make sure that your lane-mate knows that you are going and which champion you are going for. Make sure that you remember to activate On The Hunt if you know you can get a kill. Once you have a Berserker's Greaves and a B. F. Sword, it should not be long before they lose their first tower. Sivir is a very good character for top and bottom as well as mid. The problem with her laning with another champion is that she greatly gold deprives her ally. Also, I believe that very few champions deserve mid over an experienced Sivir.

If the other person on your team who wants to solo is extremely uncomfortable with doing 1v1 top, its better to take the 1v1 top than 2v2 bottom. However, I greatly prefer to have the mid 1v1. I follow the exact same skill sequence and starting items for 1v1 top as I do for 1v1 mid and 2v2. When you are fighting 1v1 top you have to be even more careful because it is easier to get caught away from your turret if you are beyond the half-way point and you have to keep in mind that the enemy jungler could be waiting for a gank at any point except for when you see them in another lane of course. You want to keep the action on your half of the lane so that it is easier for your jungler to come up and gank.

You want to follow the same basic play-style that I describe for mid-lane 1v1. Harass early and often. If you can get a clean Boomerang Blade shot on the enemy champion without it hitting any minions on the way hurry up and take it before the enemy champion moves behind their minions. Always remember that you can move once you throw your Boomerang Blade to redirect it to hit both times or to at least make up for a miss. Always be careful about the little patch of bush in the river, especially if it is on your side. It would probably be wise to place a ward there unless you are having significant gold issues, which should not happen with Sivir. If possible, always try to wipe out the entire wave of enemy minions before you recall back to base to get items and Teleport back. This is a situation where it is perfectly fine to focus on minions with Boomerang Blade because you are about to get a mana refill anyway. This also prevents you from losing any experience in the process and keeps the enemy champion occupied until you return.

I must repeat, your first choice should be 1v1 mid-lane, but sadly you do not always get what you want. Sivir is definitely better at handling 1v2 than some other characters, but it is still a very dangerous position. Sivir is very frail, so she can be prone to turret diving. This is the primary reason why I start off with a different item set when I am laning against two. If you focus on getting catalyst the protector as soon as possible when you are in a 1v2 situation, you now have more health and you get health back each time you level up which helps to deter the enemy from tower diving. If you are fighting 1v2, you have to let your team know when you need help. They cannot be watching your lane the whole game. I still take Boomerang Blade as my first ability. At level two I grab Spell Shield as usual. The difference comes after this. You then want to focus on getting Ricochet to level three because you will spend a lot of your time turret hugging and just needing to clear our minions quickly, while keeping the enemy champions away from hitting your turret. Ricochet bouncing all around works as an ok deterant to enemy champions trying to get a few hits on your turret. However, until you start to get damage increasing items and a higher level the fourth and fifth hits would not be worth the six mana per bounce. It is more beneficial to focus on Boomerang Blade once again at this point. You will still use Boomerang Blade every once in a while to last hit and clear out the wave when it is under your turret, but Ricochet will be very helpful in clearing out minions. I get the Vampiric Scepter before Berserker's Greaves because you need to stay close to full health to deter the enemy champions from turret diving and killing you and also simply so that you can stay in lane longer. 1v2 is extremely difficult if you are playing against smart opponents. However, if you play smart, you will be one of the highest level champions with a fair amount of gold by mid-game. Sometimes, if the enemy champions are fairly tough, they will try to stand in the way of you even approaching the minion waves and only last hit so that the minions never even get to your turret. In this situation, you need to rely on last hitting with Boomerang Blade and moving in and out to use basic attacks and let Ricochet do the rest. When you see opportune moments, ping one of the enemy champions and let your jungler know that there is fresh blood to be had. This is the toughest situation for Sivir as well as most champions to be in, but I hope some of this advice helps.

Sivir is still fairly frail, especially early game. Because of this, you want to have at least one tank and one other tough character on your team. The reasoning behind this is that if your team is made up of entirely frail characters, you will very likely be one of the top priorities because of your high DPS. However, if there are a few other tough characters on your team, they can keep enemy champions occupied while taking the majority of the hits. I usually prefer to have only one other frail character on my team in most cases.
Also, it is good to have teammates with crowd-control abilities because Sivir has not ability to disable aside from items. Some great options for crowd-control would be Amumu, Blitzcrank, Cho'Gath, Heimerdinger, Lux, Malphite, Nunu & Willump, and Shen.
Finally, it is always a good idea to have at least one person on your team with a global ability if possible.

It does not matter if the tank has 1/3 health and the rest of his team has over half health, do not focus the tank. Especially as Sivir, you can just let your Ricochet take care of that. Almost always focus on the most frail champion because even if this champion is not doing the most damage, by killing this champion, the enemy now has one less champion doing damage. It is also good to focus-fire anyone who is able to able to damage multiple champions on your team at once. Lastly, if there is somebody on their team who has been absolutely destroying your team in every fight, try to get them out as soon as possible.

In Team Fights These Champions Should Be "Shot On Sight"

Akali
Anivia
Annie
Ashe
Brand
Evelynn
Fiddlesticks
Orianna
Katarina
Kennen
LeBlanc
Lux
Malzahar
Master Yi
Ryze
Shaco
Sivir
Vayne
Teemo
Twisted Fate
Veigar
Warwick

Note:It is important that you discuss with your team prior to getting into a team fight, who you are going to focus first if you are facing more than one of these champions.

Pros

-High damage to multiple targets
-Excellent farming ability early and late game
-Able to take down towers alone in a matter of seconds
-Able to chase down most fleeing enemies
-High dodge chance when mobile
-Able to drastically change the outcome of team fights if handled correctly
-Capable counter to most mids
-Able to maintain full health most of the time due to lifesteal
-Wins almost any 1v1 fight
-Unexpectedly durable for a carry
-Allows you to purchase heavy damage dealing items fairly early

Cons

-You still can be focused fired if you are not careful
-Relies heavily on spell shield, which can be hard to master
-Requires a defensive play-style at times
-Almost always a main target
-Not the most reliable escape tactics
-You will not be doing as much damage as some carries who build no defense
-If you are not careful you will have mana issues early game

This guide will remain a work in progress. As League of Legends continues to go through updates, sometimes strategies need to change to compensate. I will be consistently checking for feedback, updates, and ways to improve my guide. My primary purpose for creating this guide is to change the image of Sivir. Many players consider Sivir to be a weak player and refuse to even try her. I have found that with the right items and strategy, Sivir can be an extremely dangerous champion in any game. I have spent days constructing this guide, as well as months playing Sivir. This is a long guide and it can take a while to read, but do not let that be a reason to down-vote my guide. Try it out a few times and experience the results first-hand.
While creating this build, I looked through each of the top rated builds to observe the style that they used. Therefore, I want to thank those of you who have created those high quality guides as an example. I would also like to thank my roommate, who first suggested the idea of trying multiple Bloodthirsters on Sivir to me.

"The hunt begins."

If anyone has a great game with Sivir and wants me to post their scores here, just send me a link.

March 3 - Added chapter on Elixirs
March 5 - Added Boomerang Blade damage to list of final stats.
March 7 - Added a note in the General Gameplay chapter.
March 8 - Added two notes under the Early Game section.
March 10 - Added a secondary build for 1v2.
March 10 - Added a chapter on laning top 1v2.
March 10 - Added a chapter on laning 2v2.
March 10 - Added a chapter on laning top 1v1.
March 14 - Added a chapter for posting game stats.
March 15 - Added an awesome banner made by Plastictree to the chapter about Sivir's story.
March 17 - Modified the secondary build and the 1v2 section of the guide.
March 20 - Added Quicksilver Sash as a possible fifth item.
March 24 - Massive re-haul on the build to provide more survivability and maintain DPS.
March 28 - Modified the build order and starting items to jump-start damage capabilities.
March 28 - Added another game score.
March 29 - Inserted Stark's Fervor as the fifth item.
April 18 - Removed Heart Of Gold
June 6 - Guide Updated to fit the item build and strategy I have been phasing into.
June 18 - Added a note in the items section about possibly getting fewer than three Blades.
July 13 - Inserted Flash as a primary Summoner Spell. Also replaced gylph of celerity with Glyph of Cooldown Reduction.