Master Yi is a champion of many possibilities. He can be played either AD or AP. When played AD, he can be glass canon, tanky damage dealer or offtank. I think its best to build him as tanky damage dealer. You still have absolutely amazing damage, while having decent health with good MR and Armor..Please look at what I put on items, it will explain why you have to sell you berserker's greaves for the last item.

Keeper of the ancient art of Wuju, Master Yi is a mystical warrior from the isle of Ionia. He descended from one of the few tribes dedicated to the preservation of Wuju, a martial art founded with the principles of absolute spiritual awareness of one's self and one's enemy. When the armies of Noxus invaded Ionia, Master Yi joined in the Ionian defense to fight the craven enemy, bringing his village honor through his unparalleled mastery of the blade. The ensuing battles ravaged the land, but no conflict inflicted as much horror as the day the armies of Noxus closed in on Yi's village. Left undefended, the village became the unfortunate test subject of the latest invention by an up-and-coming chemist, now known as Singed. The remains of the village that Master Yi returned to were so horrific that it remains a festering scar on Ionian history. To this day, no Ionian will ever publicly speak of what occurred.

After the Noxian invasion was contained, Master Yi fell into a deep isolation. For years, he trained morning to night, speaking to no one and refusing offers of consolation by fellow Ionians. The only thing stopping him from madly charging into Noxus battle lines headfirst was his pledge to keep the Wuju style alive. Even though he seethed with impatience, his rage became a tool for sharpening his practice of Wuju, developing stronger and deadlier skills for his eventual vengeance. The only thing that roused him was news of the League's formation, and Noxus's subsequent enrollment in the League. Master Yi now brings his mastery of the blade to the League of Legends with unflinching purpose: to avenge his kinfolk and end the predations of the Noxus once and for all.

"The art of Wuju lives on in Master Yi, and is plunged through the hearts of his foes."

Release Date: October 27, 2009
Attributes: Carry, Melee
Cost: 450 IP Points or 260 RP Points

Health Average
Attack Strong
Spells Weak
Difficulty Easy


Health 444 (+ 86 per Level)
Health Regen 6.75 (+ 0.65 per Level)
Mana 199 (+ 36 per Level)
Mana Regen 6.5 (+ 0.5 per Level)
Attack Damage 55.12 (+ 3.1 per Level)
Armor 16.3 (+ 3.7 per Level)
Magic Resistance 30 (+ 1.25 per Level)
Attack Speed 0.679 (+ 2.8% per Level)
Range 125
Movement speed 330

Pros

Great pusher/tower/farmer destroyer
Pretty easy to learn overall
Great escape/chase mechanism
CD resets/halves when you get a kill/assist(if Highlander active at that moment)





Cons

Vulnerable to disables like blind, stun,suppress...
Low HP poll until you get Frozen Mallet(or other HP item)
Not so great in team fights

Not so great in team fights

You should not initiate first. Master Yi is already squishy and if you go first, you won't do anything for your team except feed enemies. Enter the battle after your main tank and try to focus squishy champions like AD carries and AP carries first. If they have more than few squishy champions, try to focus one that have huge CC availability like Malzahar. For more in deapth instructions about team fights read gameplay section.



Vulnerability to disables

Master Yi's vulnerability to CC is one of his biggest flaws. To be realistic, this flaw is very hard to be fixed via items, runes, spells and masteries. I try to counter this flaw by taking Quicksilver Sash and situational defensive items like Banshee's Veil.


Low HP tool

Master Yi has pretty low HP base when it comes to Melee AD carries. At level 18, his basic HP is just under 2000. The best item IMO to counter this con is Frozen Mallet. Its good for you on defensive and offensive side, by granting you both massive health and AD + slow.

Marks:
Greater Mark of Desolation: I wouldn't say that anything should replace these runes, Armor penetration is really important. Lately I've been seeing a lot of armor stacking off-tanks, and you need Greater Mark of Desolation to counter them, Armor Penetration is very important for Caitlyn. Yet there is one kind of Marks that I accept (but I do not recommend, which will be listed now.
Greater Mark of Strength: The Attack Damage is sweet for an AD-Carry, nothing wrong with them. I just find armor penetration a bit more important.

Seals:
Greater Seal of Resilience: Drag these runes with you into the game, to make you more tough versus the enemy AD-carry. The extra armor that it grants you, will make you feel less squishy.
Greater Seal of Alacrity: Is one of my favorites, attack speed goes hand in hand with Headshot. In a team fight or a 1v1/2v2 situation you need your passive to deal extra damage, which why attack speed fits Caitlyn perfect.
Greater Seal of Strength: A viable choice too. Flat Attack damage makes you shine early game, and should be taken if you do not have attack speed Seals.
Greater Seal of Clarity: Mana regen is nice, I mostly use this when I'm playing Miss Fortune or Ashe, allows you to spam your abilities a bit more than usual. Helps you with harass early game.

Glyphs:
Greater Glyph of Warding: Thanks to the community, I decided to give these runes a chance, as they make you more tanky against the enemy support as well.
Early game a decent Sona will zone you due to her high damage early game, so I pick these glyphs to counter a supports early-game damage.
Greater Glyph of Alacrity: Attack speed, once again a nice partner to Headshot.

Quintessences:
Greater Quintessence of Desolation: Once again, Armor Penetration. I love Armor Penetration ;) But I since you have armor penetration in Marks and lack Attack damage in Seals, I suggest taking 1 Greater Quintessence of Desolation.
Greater Quintessence of Strength: The other 2 Quint slots should be filled out by Greater Quintessence of Strength. You lack Attack damage now, so go with the following in Quintessence.
1 Greater Quintessence of Desolation.
2 Greater Quintessence of Strength.

Your rune page should look like this, if you follow my main choices:

21/9/0 Pretty common for an AD-Carry, for the high damage output, and better survival
You can also choose to go 21/0/9 for more utility, but I recommend going 21/9/0

It took me a few days before realizing what was the best choices in the masteries, took a few things wrong, but I quickly came to the conclusion that going 21/9/0 was the best way to roll, and where I should use my points after recommended masteries.

Offence

Summoner's Wrath 1/1 to improve Exhaust, and beats Butcher.
Brute Force 3/3, improved Attack Damage. You do not need Butcher if skilled at last hitting minions. And what else should you pick Mental Force? Nah, your kidding me.
Alacrity 4/4 to get Weapon Expertise + The Attack Speed is nice.
Deadliness 4/4 to get Lethality + it grants 4% Critical Strike Chance.
Weapon Expertise 1/1 this is a MUST. 10% Armor Penetration is really good, since they are so many armor stacking off-tanks lately.
Lethality 1/1 +10% Critical Strike Damage.. Uhh, High crits <3.
Vampirism 3/3, 3% Life steal doesn't seem like much but I favor it more than Havoc.
Sunder 3/3, +6 Armor Penetration. Armor Penetration is important! Shred through their armor.
Executioner 1/1. I love this one, mixed up with Caitlyns Ace in the Hole.
6% more damage on people below 40% Health, might be what made the difference on getting that kill or not.


Defence
Resistance 1/3, You are going bot-lane versus an AD-carry which means that Hardiness is more important.
Hardiness 3/3, to increase your armor and take less damage from the enemy AD-carry.
Durability 4/4. Increases your health, but I take this so I can get Veteran's Scars.
Veteran's Scars 1/1. 30+ Health might not seem like a lot, but it will make the difference early game on a kill or surviving.

Double Strike
Master Yi strikes twice every 7th attack, this passive is a beast when it comes to Melee DPS champions. Because this build is critical damage based, your critical is doubled every seven attacks. Also with your ultimate and items you have a lot of Attack Speed, so these 7 attacks are happen in matter of seconds.

Tips and tricks:
Try to stack your double strike before you gank so you hit double damage with first attack.


Alpha Strike
Master Yi leaps across the battlefield with blinding speed, dealing magic damage to multiple units in his path with a chance to deal bonus magic damage to minions.

An amazing tool for jungling, farming, escaping and catching up. This skill allows you to pass by wolfs and wraiths in matter of 1 or 2 seconds. When maxed deals 300 damage, which is respectable, since you're not building on AP.

Tips and Tricks:
There is a picture explanation on how to use Alpha Strike in Gameplay section


Meditate
Master Yi rejuvinates his body by focus of mind, restoring health and increasing his armor and magic resistance for a short time.

Even thou I leave Meditate for last, its an incredible tool on Master Yi because of his squishiness and vulnerability. This skill is mostly underrated on most players.When at level 5 it heals you for 700 over 5 seconds, and in that time grants 300 Magic Resistance and Armor.

Tips and Tricks:
This skill grants you 300 Magic Resistance and Armor. Use it wisely against champions like Karthus when they use requirem.
This tool is amazing when it comes to survivability with low HP. You can trick your enemies into towerdiving you, granting yourself an easy kill.

Wuju Style
Master Yi becomes skilled in the art of Wuju, passively increasing the power of his physical attacks. Activating Wuju Style doubles the passive bonus damage for a short time, but the passive bonus is temporarily removed after the effect wears off.

This is pure ownage skill on Master Yi. Because of massive amounts of AD that this skill provides, I first take Phantom Dancer providing Attack Speed and Critical Chance. At level 5 only passive already gives 35 AD. When activated, you get 70 AD boost for 10 seconds.

Tips and tricks:
Since last patch, this skill can be actived when in Alpha Strike form. Activate it while you're in Alpha Strike so your first hit will be affected by bonus.




Master Yi moves with unparalleled agility, temporarily increasing Master Yi's movement and attack speeds as well as making him immune to all slowing effects. Additionally, killing a Champion refreshes all of Master Yi's cooldowns.

This skill is epic. This is your chase, escape and kill resource. You have a problem with enemies chasing you? Press R. Your enemies too fast for you? Press R. Not dealing damage fast enough? Press R. For what it offers, it has low cooldown. When maxed it gives 40% Movement Speed and 80% Attack Speed for 12 seconds. If thats not enough, this skill makes you slow immune when active.

Tips and tricks:
If you kill an enemy during Highlander is active, all your cooldowns drop to 0 and you're skills are available again.
Combined with Wuju Style this skill is pure beast dealing damage in fast time frame. Use this in your advantage and backdoor when possible..

Boots of speed - Master Yi is always chosen as first sight for enemies because he is an over powered champion in late games and that is why they try to anticipate, that is why boots of speed is handy. You can have more faster ways of escaping, plus this is a faster way of catching up and it is a build up item following up towards berserker's greaves (a mid item useful only until last item).


2 Health Potions - These two are useful in case either you are facing champions which are ranged, giving them a chance to hit you further away even if you are near a turret without the ranged champions receiving any damage at all. On the other hand the other reason is you have took quite a lot of damage without earning hardly any experience and you need to use them to stay without recalling for a decent amount of time.


1 Mana Potion - Master Yi's abilities cost high amounts of mana which Master Yi has limited. Only to be used when mana is completely low.

Berserker's Greaves - As before you might have seen the item list, and it has 6 last items. It means you have to sell your worst item when you have a sufficient amount of gold for your last item on the list. The worst item is Berserker's Greaves, but you still have to buy Berserker's Greaves for early gaming so you can catch up to fights faster and leave faster. However if you want to know the true facts on why you have to sell Berserker's Greaves for a Phantom Dancer,I will oblige on the next chapter (Full End Items).


Zeal - You need the effects of Phantom dancer, but you need damage by then (Infinite Edge). So that is why you should buy the small effect (Zeal).

The following 3 items, should be picked almost no matter the situation. I will list a few Recommended builds versus the different kind of teams you can meet (AD, AP, Tanks) soon.
But for now, keep in mind to get these 3 items as they have a huge impact on your damage output:

Infinity Edge - This item is very expensive, but is worth it and should be bought very early. It provides you so much AD, crit and an unique passive increasing the damage of your critical blows by 250% instead of 200%. Your enemies will fear you very early in the game.


The Bloodthirster - This is the part where people start to realize harassing you in the lane will be in vain, a few auto-hits and you managed to regain the health you lost. With this baby stacked full up, you will be unstopable with an extremely high damage output. If I end up in a lane without a healer, I usually pick The Bloodthirster before Infinity Edge due to the lifesteal. Only con about this item, is that you lose your bonus stacks on deaths. You can use many of these because it has only a passive (passives can multiply, unique passives cannot).


Phantom Dancer - Phantom Dancer mixed up with infinity edge is a dangerous cocktail. Bestows you attack speed as well as critical chance with fits perfect with Infinity Edge + It grants you a nice movement speed so that you can outrun most enemies that are chasing you / you are chasing them. Phantom dancers apply a short amount of movement speed. 3 Phantom dancers would be equal to (enchanted 2), so that is why you can sell you berserker's greaves.

Primary Summoner Spells


Flash and Exhaust are my most recommended summoenr spells for Caitlyn. And should be carried with you into almost every single game, but there are certain occasions where you should pick something else, which I will mention soon.

Flash:The reason I enjoy Flash is due to the great escape and chase mechanism you get. This summoner spell can get you out of a sticky situation, where you accidently went too far.
Flash can also grant you a swift kill - The enemy is on very low health, 1 auto-hit is enough to get you a kill, that is where you Flash in range and right click on your target.
According to me, it is one of the most important summoner spells in the game.
Pros: Early damage,Great finisher and Counters heals.
Cons: Short Range.


Exhaust: If you have to face against an opponent who is faster than you, or deals high DPS, you'll want to pick up this. You'll significantly lower their DPS, and perhaps allow you to destroy them, or slow and use it to escape.
Pros: Anti-DPS, Strong Slow and Damage reduction.
Cons: Cleansable.

Apparently this summoner spell is used by a few Caitlyn players, but I am not a fan of it. I like ghost and I see it as a good choice for OTHER champions. Just not Caitlyn. There are those who likes the Flash/ Ghost combo, for a nice movement speed and good chase/escape options. I'm just not a fan of it, and see other summoner spells that fits her better.














Many AD Carries are using this spell lately, to counter all those CC teams. I'm not a fan of it, if they only have 1-2 weak CC abilities, go with Exhaust. But Cleanse gets you out of a bad situation and helps you get away from a CC filled team. Then you should pick Cleanse asap, no discussion. If Rammus first gets you with Puncturing Taunt you're doomed, unless you have Cleanse to help you get away in time.











I recommend this for new Caitlyn players or going mid-lane, and maybe those who are unlucky enough to get a non-support partner.
Teleport lets you get back in the lane quickly after recalling, which also means you gain more exp and farm due to getting back to your lane fast, and can help you keep up with the xp if you are having problems in the laning phase.




Those summoner spells that I did NOT list, should not be used no matter the situation. So I won't bother to waste time on listing them, and why you shouldn't pick them.
If you disagree on me with anything please feel free to inform me.

Also in conclusion I hope this build helped you on your path of becoming a good Master Yi player. Judging on comments I think I inspired both starters and veterans for Master Yi and helped them to a point at which they know how to play Master Yi. I saw a few pictures from players that used this build, and in some cases my build really helped them. Let me tell you that there is nothing better than hearing that your build worked for most of those people that used it. I had a feedback section with comments/pictures, but eventually there was too many thanks or pictures to post so I deleted that chapter.If anybody is waiting for Domition section, I doubt I'll be taking that subject. I dislike Dominiom gamemode and so, I don't play it.