Xin Zhao Build Guide by MRxMONEY
Not Updated For Current Season
Xin Zhao Build
(1) Core Build
Example Full Build (Damage Heavy)
Example Full Build (Tank)
Example Full Build (Tank into Damage)
Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Threats to Xin Zhao with this build
Xin Zhao - The Seneschal of Demacia
Welcome to my guide on playing jungle Xin Zhao. I want to first say thank you for checking out my guide and I appreciate any feedback that you have on it.
With that said, if you already have a Xin Zhao guide then please be respectful to me and others by not down voting the guide while trying to get a higher rating on yours. I promise you that I have spent a tremendous amount of time on this guide as well as playing Xin Zhao so the info is up to date and as helpful as possible. I also want everyone to know that I do not believe there is a "one build fits all" for Xin Zhao or any champion that works every single game and there are many items that I believe work very well on him. This guide is just my specific item based approach to winning more games with Xin Zhao. My builds and jungle viewpoints are based on 500+ normal and ranked games that I have played this champion so if you use this guide correctly it should help you get more wins and improve your jungling skills too.
I also want to say that Xin Zhao was my most picked jungle champion in season 3 and I carried myself to platinum 1 with him alone so you can easily gain ELO with this champion if you put in the time. I believe Xin Zhao is a very viable jungler in the current meta however he definitely shines more in bronze to gold ELO and becomes less viable in higher plat and diamond level gameplay. With that said, there are definitely other champions that have great initiation, faster farming and/or better utility making them a preferred choice over Xin Zhao for the current meta. I have also included a jungle tier list in the guide if you are interested in other top junglers too.
If you are already a jungler then you probably dont care about the info in my guide so feel free to just use my item builds as you wish. If you are new to jungling and looking for a lot of good info then this guide will definitely help you out.
More on these builds below as well as in game strategies for you.
PS: PLEASE RATE AND COMMENT!
''Death is inevitable; one can only avoid defeat.''
-- Xin Zhao
Pros / Cons
- Strong early game
- No skill shot abilities
- Great jungle sustain
- Easy to gank once your level 3
- Sticks to targets well
The biggest strengths of Xin Zhao are in his early game pressure because his ganks are beastly during laneing phase. This also makes him one of the strongest duelists at level 3 with double buffs. I classify Xin Zhao as a gank heavy early game jungler that transitions into a tanky team fight initiator mid and late game.
- All in fighter
- Base damage output is weak
- Tends to get focused first in team fights
- No escape abilities
- Weak late game
The biggest weaknesses of Xin Zhao are his lack of mobility outside of initiating onto a target because his kit is rather weak in utility late game compared to other champions. Another weakness he has is being very auto attack reliant for his kit/cooldowns to work efficiently and deal damage. He is somewhat reliant on snowballing games as he tends to fall off mid to late game especially if he gets behind.
Runes, Masteries, & Sumoner Spells
Greater Mark of Attack Damage
Greater Seal of Scaling Armor
Greater Glyph of Scaling Cooldown Reduction
Greater Quintessence of Attack Speed
Greater Mark of Attack Damage - I take Attack Damage Marks for a few reasons, they give you faster clears in the jungle and more damage early on for ganking. You could also take Greater Mark of Attack Speed but then your damage output would be fairly low early on giving the edge to the enemy jungler in 1v1 fights with them.
Greater Seal of Scaling Armor - I take Scaling Armor Seals for a few reasons, First is you actually dont need flat armor in the jungle now due to the new passive on Hunter's Machete. I also take two mastery points in Tough Skin which reduces quite a bit more damage from jungle camps. The last reason is because with scaling armor you will get 27 armor at level 18 over 9 flat armor at level 1 with Greater Seal of Armor. This means by level 6 you will have 9 armor from your Greater Seal of Scaling Armor so once you get to level 6 then these are all around better than Greater Seal of Armor.
Greater Glyph of Scaling Cooldown Reduction - I take Greater Glyph of Scaling Cooldown Reduction because CDR scales with his kit exceptionally well giving him more damage as well as chase potential and knock-ups. The Scaling CDR also stacks with your 4 points in Sorcery giving you 10% at level 6, 15% at level 12, and 20% at level 18. This in combination with your jungle item puts you at 30%. If you add in a possible Ancient Golem blue buff, The Brutalizer, or even an Elixir of Brilliance you can get to max 40% CDR very easily at full build. The only other Glyphs I would go are Greater Glyph of Scaling Magic Resist if you are up against an enemy team that has a bunch of magic damage but all in all I still think CDR is way better on Xin Zhao.
Greater Quintessence of Attack Speed - I take attack speed Quints for faster clears in the jungle, quicker procs on your three talon strike combo, stacks with other items in your build and gives you more heals from the passive on Battle Cry. These Quints recently got changed from 3.3% attack speed to 4.5% so the slight buff makes them more worthy than damage Quints. The other Quints that would be viable are Greater Quintessence of Attack Damage or Greater Quintessence of Armor Penetration but neither are quite as good.
Primary Offensive Masteries
For the offensive tree I put 9 points in it. I put 4 points in Sorcery because I value 5% cooldown over the 5% attack speed you would get from taking 4 points in Fury . The Second reason is if you take Greater Glyph of Scaling Cooldown Reduction they would give you 15% CDR at level 18 and stack with your 4 points in Sorcery giving you 20% total. I put one point in Double-Edged Sword because this help you deal more damage all around and there is nothing else better to put this point into. The next two points I put into Butcher and Feast for slightly faster farming as well as mana and health return when killing camps. The next four points I put Brute Force and Martial Mastery for the slightly extra attack damage early and late game which scales well with your build and because you're and AD champion. The next 4 points I put into Executioner and Dangerous Game which raises your kill potential and gives you a little health and mana on kill which could save your life or just allow you to continue with a gank or team fight. I put too points into Executioner and Dangerous Game because I actually dont like putting points into Warlord seeing how I dont build full ad so you dont get much bonus ad from this mastery. The last 4 points I put into Devastating Strikes and Havoc to increase your armor penetration as well as overall damage giving you more kill potential. There are not a lot of mastery paths to take when going 21-9 but this is my preferred setup.
For the defensive tree I put the remain 21 points in it. The first two points I put in Enchanted Armor because they increase the bonuses you get from the Armor and Magic Resist in your build and because this is way better than putting these two points into Recovery just for a little bit of health regen. The next three points I put in Tough Skin and Bladed Armor because it reduces quite a bit of damage you will take while farming your jungle and helps you clear camps just a little faster, mainly buffs and dragon. The next 4 points I put into Veteran Scars and Juggernaut because they increase your base and overall health % by about 160 late game which is pretty good and the best masteries to take if you only have 9 points left.
Alternate Defensive Masteries
If you dont feel comfortable going 21 points in Offense then take 21 points in defense and 9 points in offense which will give you a little more defensive stats and tankyness and slightly less kill potential. If you are more experienced jungler then definitely go 21-9-0 because this setup allows you to snowball much better early on. I would only recommend going 9-21-0 if you are newer to jungle Xin Zhao and haven't fully mastered his limits.
For the offensive tree I put 9 points in it. I put 4 points in Sorcery because I value 5% cooldown over the 5% attack speed you would get from taking 4 points in Fury . The Second reason is if you take Greater Glyph of Scaling Cooldown Reduction they would give you 15% CDR at level 18 and stack with your 4 points in Sorcery giving you 20% total. I put one point in Double-Edged Sword over something like Butcher because this help you deal more damage all around than just a little more damage to minions. I take the other 5 points in Brute Force and Martial Mastery for the slightly extra attack damage early on which give you faster camps clears and more damage on ganks and because there is really nothing else that is good to get in the offensive tree then those two when you only have 9 points.
For the defensive tree I put the remain 21 points in it. The first two points I put in Enchanted Armor because they increase the bonuses you get from the Armor and Magic Resist in your build and because this is way better than putting these two points into Recovery just for a little bit of health regen. The next three points I put in Tough Skin and Bladed Armor because it reduces quite a bit of damage you will take while farming your jungle and helps you clear camps just a little faster, mainly buffs and dragon. The next 4 points I put into Veteran Scars and Juggernaut because they increase your base and overall health % by about 160 late game which is pretty good and because you need to put 9 points into defense to get the higher masteries in the defensive table. The next six points I put into Hardiness and Resistance which give you a little bit more flat armor and magic resist which is nice throughout the game and because you build fairly squishy early on. The next point you can put into Swiftness , Reinforced Armor , or Evasive , pretty much whatever is your preferred mastery to have of the three. I dont think it matters all that much but if it dose then just change this up while in the game lobby to best help you against the enemy comp that you would be facing. The reason I choose to put this into Swiftness is because I think slows hurt Xin in team fights and could mean the difference of landing your Three Talon Strike combo. If you prefer a little bit more damage reduction against crits or AOE spells than either Reinforced Armor or Evasive are good to take too. The remaining 5 points I put into Legendary Guardian and Tenacious because they are really the best masteries in the defensive tree and the reason I put 21 points into it. I dont take masteries like Oppression , Perseverance, Second Wind , or Runic Blessing because you only get 21 points and these are all weaker than the ones I take.
As a Jungler you will take smite for obvious reasons. you need it to secure your buffs as well as dragon and baron when your team decides to take those objectives.
The reason I take Ghost instead of Flash is because I highly value movement speed on Xin Zhao for early game ganking and snowballing the game. It also has a lower cooldown than Flash so you get more effective ganks/escapes early on. Now with that said, Ghost is a lot more dangerous than Flash so if you're not that experienced with playing Xin Zhao then dont take Ghost. As far as late game team fights I think that Ghost works very well but definitely a very different play style than having flash. Once you get used to what you like most then go with that one and if you are new to Xin Zhao then you may just want to start with Flash and work your way to Ghost down the road.
This is a more common Summoner Spell to have on Xin Zhao so if you prefer it or are new to playing him so just go with whatever you're most comfortable with.
The way I level up my abilities is Q>E>W. I dont count leveling up R because that is your ultimate and you will get this at 6, 11, and 16 every game. I level up Three Talon Strike first because it is your main damage ability making your dueling potential a lot stronger. Leveling this up also lowers the cooldown on this ability from 9-5 seconds which in turn lowers all other ability cooldowns too. I level up Audacious Charge second because it's your gap closer and the best way to stick to your target so having the cooldown go from 14 to 10 seconds and the slow go from 25% to 45% at max rank is really important when ganking or engaging team fights mid to late game. I level up Battle Cry last because you get the passive heal just from having one point in it. You also get 40% attack speed boost with just one point which is enough to land your full combo on a target so there is no real need to level this up any sooner.
Ability Combos (Ganking without your ultimate):
Ability Combo #1 - ( Audacious Charge, Three Talon Strike, Battle Cry) This is the easiest way to gank a lane which gives you a good gap closer. The problem with using your abilities in this order is the enemy can use flash or even an ability to get away. If the enemy has an ability they can use to escape then this might not be the best combo to use and I would try (Q, W, then a delayed E see below). If the enemy champion your ganking doesn't have flash, an escape/stun ability then this combo is almost always a guaranteed kill if you can get in range to use Audacious Charge.
Ability Combo #2 - ( Three Talon Strike, Battle Cry, then a delayed Audacious Charge) This is the second way I will gank a lane. It does require you to get behind the enemy or flank from the side to pull off which can be a little more tricky to do. This is the best way to gank someone that has an escape ability or even flash to get away. When pulling this off you will want to walk up to the enemy and use Three Talon Strike + Battle Cry, then when they use flash or an ability to get away I will jump on them with Audacious Charge.
Ability Combos (Ganking or team fights with your ultimate):
Ability Combo #1 - ( Audacious Charge, Crescent Sweep, Three Talon Strike, Battle Cry) This is the easiest way to initiate a team fight or gank. This is very effective when you are diving into the middle of a bunch of enemy champions. Not only does your Crescent Sweep hit more enemy's giving you better armor and magic resist for 6 seconds but it will isolate that target from the rest of the enemy team. This can allow other members on your team to focus the same target without other enemies getting in the way.
Ability Combo #2 - ( Crescent Sweep, Three Talon Strike, Battle Cry, Audacious Charge) This is the second combo I will use when my ultimate is up, which is a little more tricky to pull off, it requires you to get behind your target so you can flank or use flash to pull this off, then use your ultimate to knock them towards your team. You can then walk up to them and use (Q, W, delayed E) or just (E, Q, W) right onto them after using Crescent Sweep to reposition them.
What a lot of people don't know about Xin Zhao is the defensive stats he gets from his ultimate, Crescent Sweep. For each champion he hits it gives him temporary bonus armor and magic resistance making him an insta-tank for 6 seconds as well as a massive disruption in fights. This is one of the strong reasons why he is such an awesome initiator because the enemy team will usually focus the first diver so having bonus resistances during that initiation window helps out a lot. Another tactic Crescent Sweep can be used for is to get divers off your carries but either way its a very powerful tool in his kit weather you're initiating, counter diving, or protecting the carries in team fights.
Helpful Tips & Tactics
This is a section where I have included all the basic and advanced strategies/tips I have learned over the years of playing Xin Zhao and should help you out a lot. This list is in a completely random order that I have build over time and just meant for players trying to learn more.
- Avoid using you Audacious Charge when farming jungle camps. It doesn't do that much damage and it cost quite a bit a mana which can prevent you from ganking or being able to team fight if you "go ooom" (run out of mana).
- Avoid counter jungling unless you know where the enemy jungler or enemy laners are on the map. This is because Xin does not have an escape without flash and can be collapsed on quite easily.
- Pay attention to the positioning of your team. Xin is one of the easiest champion in the game to initiate with but because you have a gap closer this can easily put you in a bad position away from your team meaning they cant support you or follow up on your engage which make it easy for the enemy team to blow you up first in fights.
- Pick one lane at the start of the game that you want to snowball and gank it as much as possible, this is because Xin is one of the most powerful early game gankers in the game and can punish champions that dont have flash to escape. Use this to your advantage to snowball a lane on your team.
- Avoid fighting bad or neutral fights when you dont have flash up, this is because Xin lacks escapes and can die quite easily when out of position.
- For team fighting, pick one target that you want to take out of team fights and engage on them every time if possible. Xin is extremely powerful when in someone's face and stick to a target very easily. Use this to your advantage to take a specific target out of a fight or just cause them to have to focus you first.
- Use your ultimate to for a multiple target disruption on an engage, peeling for your carries or as an escape if you engage wrong instead of just extra damage on a target/s because it utility and knockback is much stronger than the damage it deals to the enemy team.
- If you fall behind dont force fights/picks or even spend a lot of time around your team holding towers. Let the mid laner and other wave clearer on your team do that. Xin is actually a decent split pusher because you can take down towers really quickly with your Battle Cry and Three Talon Strike when left alone. Also if you split push when behind you can sometimes cause the enemy team to not group and push objectives which can stall the game for your team too.
Early Game Jungle Tips
A good strategy is to gank top lane first and try to snowball that lane so you can leave them alone and camp mid/bot which leads to dragon control. If my top lane is losing then I will usually ignore them and try to snowball my carries. If you do try to help top make sure your bot lane has dragon control, if you dont you will likely lose that objective. Either way, you always want to communicate that with your top laner so they dont start raging at you and blaming you the whole game. A huge tip if your ganking a lane is knowing where wards are placed, otherwise you can waste a lot of time in the process. To do this simply ask your laners if they know where the wards are placed and keep tabs on whether the laners are buying wards and placing them. You can also check if they have placed their trinket ward by pressing tab and running your cursor over their trinket. Another tactic you can use is approach a lane and watch the movement of the laner/s which can sometimes tell you if an area is warded. The other big tip for ganking is checking if the enemy laners are on the mini map. Doing this reduces the amount of enemies that can counter gank you to just the enemy jungler. To have the best vision of an enemy jungler ward their wraith camp and/or exists to their jungle. This will give you better ganks as well as be in position to counter gank. For the most effective ganking, keep track of flashes and try to continuously gank lanes where they dont have summoner spells up. This will lead to a lot more kills for you and your team as well as causing the enemy laners to play safer which usually denies creeps from them. If a lane is snowballing really hard you dont want to put a lot of time into ganking for them but you do want to protect them from counter gank as much as possible because they will usually be the highest priority target to a jungler and mid laner. At the start of every game I will usually pick one lane that you can camp and carry the game with. If done successfully, this leads to that lane snowballing which allows them to help out other lanes with you or just carry the game late. I usually wont pick top lane for this and typically dont spend a lot of time top lane either. This is because if you are seen top you will likely give up a free dragon to the enemy. If lanes are missing try to counter gank where you thing they are going to be or ping your lanes for safety even if the ping is wrong it's still better to guess and be wrong then not ping at all. If you choose to invade the enemy jungle, you want to make sure you are stronger than them and I dont suggest doing this if you dont know where the enemy laners are. Otherwise you can be ganked by multiple people or put your laners in a bad position when they come to help. Outside ganking for your team, the two make objectives early on is killing dragon and covering tier one towers. Mid lane tower is by far the most important one to defend for as long as you can because it give you the best control of your jungle.
Team fighting, proper positioning, and how to initiate fights correctly
HOW TO INITIATE CORRECTLY
The best way to initiate fights late game is by flanking the enemy team and getting behind them. The are a few reasons why this is the proper way to initiate with Xin Zhao. The first is because it allows you to initiate on the right target and apply your 15% armor reduction from Challenge and 45% slow from Audacious Charge. The next reason is this ensures more targets will be hit with your ultimate Crescent Sweep giving you more bonus armor and magic resist on the initiation. The last reason you want to flank the enemy team is because it allows you to use your Crescent Sweep before or after Audacious Charge to knock enemies away from you or just reposition them. If the carry you are initiating on doesn't have flash or an escape them its almost always a kill if your team can follow up. If they have or an escape or flash up then I would use Crescent Sweep to knock them into your team and then follow up with the rest of your combo.
HOW TO INITIATE POORLY
The biggest mistake I see Xin Zhao players make late game is they sit on the front line and initiate straight at the enemy team. This sometimes works against disorganized teams or against teams that have little to no CC but from my experience this is the wrong strategy to use when initiating with Xin Zhao. This is because he is all about setting up picks, flanking the enemy team in fights, and disrupting the enemy carries positioning on the back line with his ultimate. The first reason you dont want to sit on the front line is because you will take a lot of unnecessary poke damage making you much weaker once a full team fights breaks out. The second reason is you dont provide much wave clear so their is little to no reason for you to be there. The third reason is initiating directly into a team that can see you makes it easy for them to land their CC which makes it easy to kill you, protect their carries, or just disengage the fight. And the final reason is because your ultimate Crescent Sweep knocks back the enemy team which can push them away from your team not allowing them to follow up especially if the target you initiate on flashes away.
WHAT TO DO AFTER YOU INITIATE THE FIGHT
After you initiate a fight, you will often get focused and bursted down to a low amount of hp. The way you want to play out a full team fight is land your full combo then peel back to your carries and wait for cooldowns to come back up. Try not to stand their tanking free damage. This dose a few things for you and your team. The first is it causes the enemy team to either keep fighting or back off sometimes catching the enemy team off guard or committing to hard to a counter dive. The second thing is this allows you to use your second set of combos on enemy champions that are diving your carries. Now Xin Zhao is not known for peeling for his back line but he is actually quite strong at this. That is because he has a 45% slow, a knock-up, and 15% armor penetration from Challenge. Because of these abilities and your very low cooldowns you are actually extremely effective when standing between your ADC and whoever is trying to kill them. With that said, this is just a secondary tactic to use in team fights. You will still want to be the primary initiator if possible and always focus on flanking behind teams, not just sitting on the back line peeling for your carries.
Through my experience of playing Xin Zhao, I have settled on a specific set of items that work very well for pretty much every game. I dont try and get too fancy with my item paths, I just keep it simple but at the same time, I never just build the same 5-6 items every game either. The way I like to build tanky AD junglers is a step by step choose your own build with simple item options. Below I have broken down each item with short explanation and its value to Xin Zhao as well why or when you would build it.
(1) Core Build
Spirit of the Elder Lizard
Boots of Speed
Warding Totem - I start with this trinket because it helps with vision against early buff invades and counter jungling or just trying to keep tabs on the enemy jungler.
Hunter's Machete - This is a standard start for every jungler in the meta today along with 4x Health Potion's so you can clear your jungle, gets buffs and possibly gank a lane or two depending on what happens.
Spirit Stone - This is the first item I will get when you back to base along with a Spirit Stone or two as well as wards and pots if needed. This item gives you pretty good sustain in the jungle for farming camps and builds into your Spirit of the Elder Lizard.
Spirit of the Elder Lizard - I get this as my main jungle item because it give you a lot of damage early on for ganking and farming your jungle which allows you to snowball the game better than any other jungle item. Because Xin Zhao is an early game jungler I prefer this item over the rest because the damage power spike on this item is really strong for ganking as well as dueling the enemy jungler. I also recently switch my build from a Spirit of the Ancient Golem over to a Spirit of the Elder Lizard because the Spirit of the Ancient Golem is now meant more for full tank junglers. I also switch from a Spirit of the Ancient Golem because it no longer gives you tenacity so its worth is a lot lower on Xin Zhao now.
Giant's Belt - I pick this up as part of my core build because I will get a Randuin's Omen every game and sometimes a Warmog's Armor so this build into both those items. I also get this as part of my core build because I switched over to a Spirit of the Elder Lizard from a Spirit of the Ancient Golem which used to give you 350 HP early on so the Giant's Belt makes up for this HP difference and still makes you just as tanky early on in the game.
Sweeping Lens - I switch over to this trinket as part of my core build because it allows you to clear wards for ganking lanes, taking dragon and baron, as well as setting up picks mid and late game.
(2) Boots (Pick One)
Mercury's Treads - These are the boots you will want to go 80% of games because if gives you tenacity which is a must have most of the time as well as some early magic resist which gives you a little defense against AP damage. However if you are up against a team that is full AD then you probably dont want these boots considering most AD champs dont have much CC.
Ninja Tabi - This boots are great for a couple reasons. The first is if you're up against a full AD enemy team and the second is if you enemy AD carry is the only one fed on their team. You can also get away with these boots if the enemy team lacks hard CC and you dont need tenacity for team fights.
(3) Mid Game (Pick One)
Trinity Force - This is the best damage item to build on Xin Zhao because you have high CDR and low cooldowns which give you a lot of passive damage from the Sheen damage. Xin Zhao also uses all stats this item provides really well which makes it amazing on him. Another reason this item works so well is the passive movement speed from auto attack targets which helps you land your full combo and stick to targets that much better. If you prefer to go more of a damage heavy build or you have a full tank top laner then this is definitely the right items path for you to take.
Warmog's Armor - This is a secondary option to take which makes you very tanky early on in the game just giving you raw HP to defend against AP and AD carries damage. This builds out of the Giant's Belt in your core build and lets you build your Randuin's Omen and Banshee's Veil a lot quicker than going Trinity Force. I will go this route if I have a damage heavy top laner and my team needs me to be the main tank of the team.
(4) Defensive Items
Randuin's Omen - I always Build a Randuin's Omen because the enemy team will have an ADC on their team and this is the highest health with armor item you can buy in the game. This also lets you stick to the enemy a little better from the passive AOE slow active and provides a little attack speed slow which helps reduce some of the AD carries damage too.
Banshee's Veil - The Banshee's Veil is almost always a must buy and the best all around health and magic resist item you can buy. This is because it gives you a lot of tanky stats but the spell sheild is great for avoid a cc spell to stun or slow you as well as long range poke damage. The only reason you would not buy this item is if the enemy team comp is full AD meaning you would take little to no magic damage. In that case you would not want to build a Banshee's Veil and you would just want to get something else for defense like a Thornmail and/or Guardian Angel. Another option would be to get a Sunfire Cape if you wanted armor and health over health and MR.
(5) Finishing Items (Pick One)
Thornmail - This is actually one of my favorite defensive items to build late game because the AD carry will have full build or close too it and will be doing a lot of damage to you. This is because AD carries usually focus the closest target to them so if you initiate as the frontline then their AD carry will be hitting you. This helps deal damage to them as well as reduce a lot of physical damage that you would be taking without it.
Guardian Angel - This is a great item if you are getting focused and killed first in team fights. This should be used to soak damage without the huge risk of dying right away. The passive rebirth on this also buys your back line a little more time if you do get blown up right away. The other cool thing about this item is the enemy team can waste a lot of ultimate's trying to pop your GA which means less damage is focused at your carries and can sometimes win you team fights.
Maw of Malmortius - This is an amazing item against double AP enemy team like top, mid, and/or jungle. This is also really good against AP assassins that are focusing you from the back line. Not only is the magic resist and damage nice to have, but the 400 AP shield often times lets you get the hell out of the fights without getting 100% to zeroed.
The Black Cleaver - This is one of the better items for tanky bruisers IMO because this allows your AD carry to deal more damage to the target you are attacking. The other nice pieces to this item are it gives you CDR and health with is really good on Xin Zhao. I would only get this item over a Maw of Malmortius for one of two reasons. The first is if the enemy team is heavy AD or you are taking little to no damage from the enemy AP champions. The second reason would be if you are trying to help your teammates deal more damage to the target your fighting. This could mean another AD diver with you or if you are focusing a frontline tank helping your AD carry take them down faster.
Upgrade When Needed
Mercury's Treads - Homeguard / Ninja Tabi - Homeguard - This is just the tier three boot upgrade that I get when I want or need to at some point in the game. There isn't really a specific time that you have to get this upgrade but more when you need base defense or if you need to get to an objective like baron late game.
Oracle's Lens - This is the upgrade to your early game Sweeping Lens. Get this upgrade if you need to detect stealth units in team fights or want longer stealth vision to clear wards late game.