Build 1:

1992 hp
90,5 MR
123 armor
373,82 dmg
19,95 armor pen + 50%
attack speed: + 91%
Price for full build: 15485
Note: Cheap build with high armor penetration and some nice attack speed

Build 2:

2718 hp
114,8 mr
188 armor
409,18 dmg
21,6 armor pen + 10%
attack speed: + 50%
Price for full build: 19080
Note: Expensive build with focus on tankiness first and damage later on (decent attack speed and armor pen)

Pros

- Does tons of damage really quick with build one
- Can escape easily
- Hard to counter (a thornmail doesn't counter your lifesteal)
- Among the highest attack speed ingame
- Can be pretty tanky and still do damage

Smite] THIS IS A MUST FOR JUNGLERS !!! NEVER TAKE ANYTHING ELSE! Cleanse Many people would take Exhaust but i think and out of experience i found out Cleanse is so much better, since you will often get CC'ed to death and before your Quicksilver Sash you wouldn't be able to do much 1v1 Situational Flash Flash is a pretty great summoner spell many people like, but almost as many dislikes, it can be used for both chasing and escaping. But with Cleanse you would be able to catch up with even flashing players easily with you full build and ultimate Exhaust Exhaust can be a good spell, since you allows you to 1v1 anyone and allows you to get some better ganks

Runes

21/09/00 or 21/00/09

The 21/09/00 build:
This is the more "defensive" build and can easily be used for a fast jungle clear time and still be really healthy when you get out of the jungle and gank

The 21/00/09 build:
Since Yi doesn't really need the defensive stats utility can provide him with longer buff time, movement speed and mana regen a perfect setup for a Yi, but if you don't have flash pick Improved Recall over Summoner's Insight

- Double Strike

Master Yi strikes twice every 7th attack.

This is a Godlike! ability it allows you to hit twice in one attack which increases your damage a lot

Effetive use

To use this most effective keep it up when you want to gank and by activating Wuju Style (E) before you attack you get a double attack which both benefits from your Wuju Style - If there's multiple targets use Highlander (R) to refresh cooldown on your abilities when you kill a target (you often do)

- 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.
Master Yi leaps across the battlefield striking up to 4 enemies, dealing magic damage to each enemy with an increasing chance to deal 400 bonus magic damage to minions.

This ability allows you to clear the jungle ekstremly fast and it's your close gap when you gank

Effetive use

To use this most effective be ready to dodge ult, skillshots and everything else, it makes you untargetable which can benefit you a lot, if you're getting focused hard either use it on creeps nearby to get away or if the enemy team are about to get cc'ed to the ground find the carry, but think fast. But be careful when you use it, if the enemy predict you targeted them they can either move in between their team or even a tower cause you will appear next to them (don't ever alpha strike near their spawn platform) it also cost a lot of mana and you simply does not have that and your Highlander (ultimate) are top priority for spending your mana.

- Meditate

Master Yi rejuvinates his body by focus of mind, restoring health and increasing his armor and magic resistance for a short time.
Master Yi channels, restoring health over 5 seconds. While channeling, Master Yi gains armor and magic resistance. IT NOW SCALES 1:4!

This skill is not the very best defensive ability except if you get some AP (ability power) since the health it provides you with are really small compared to your lifesteal

Effetive use

To use this most effefive use it for healing through stuff such as ignite or other dots (damage over time) early on it can also be used against global ult like Karthus's Requiem since it gives you a ton of magic resist and armor.

- 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.
Passive: Increases physical damage

Active: Master Yi can activate this ability to double its effectiveness for 10 seconds, but this removes the passive bonus until Wuju Style becomes available again.

This is a really awesome ability which increases Master Yi's damage a whole lot if it's used right

Effetive use

To use this most effective try to keep it up all the time in a teamfight (your ult refreshes the cooldown on all abities), by using this method you can unlock the TRIPLE DAMAGE BONUS! which comes from activating your Wuju Style before you kill a person with Highlander on then don't activate it again until it's active is gone and then activate it and do it one more time !Penta's Incomning! $$ giving you a lot of cash and allows you to kill even moore

- Highlander

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.
Increases Master Yi's movement speed and Attack Speed, and he becomes immune to all slowing effects. Additionally, killing a champion refreshes all of Master Yi's cooldowns. (Assists reduce half of the base cooldown amount.)

This is probably one of the best offensive ultimates ingame IMO since it allows you to cut through enemies really fast and with a sick amount of damage from your abilities and items they drop like flies. It really fits the style of Master Yi when it comes to damage and if you have to escape nobody can catch you if you use this ability (maybe rammus)

Effetive use

Activate this abilities when you decide to join the team fight and focus down the carry he/she should be dead really quick, but be sure to kill an enemy to refresh the cooldowns on your abilties so you can reactivate this awesome ability

Starting items vampiric scepter This item allows you to survive in the jungle and farm it all day and all night or cloth armor If you want some more sustain you can go cloth armor and 5 health potions (i recommend vampiric scepter or [[boots of speed) Health potion When you bought your Cloth Armor you need sustain and here comes 5 health potions in handy or cloth armor You run around a lot and you will need speed to pull of a gank (i recommend this or Vampiric Scepter) Health potion When you bought your [boots of speed]] you need sustain and here comes 3 health potions in handy

Core items These are your main items without you're nothing but with them be ready to rape :D JK Wriggle's Lantern This item is great for jungling it gives you damage, armor, lifesteal and a free ward every 3. minute (later on replace this with bloodthirster, but only when you have full build) Berserker's Greaves Berserker's Greaves are some great boots for damage dealers i would maybe go Mercury's Treads if you're planning on using the secondary build Zeal This is a pretty decent item, which gives you all Master Yi needs (later upgrade this to an Phantom Dancer. Infinity Edge This is probably the best offensive item in the whole game, giving you tons of attack damage, some nice crit and a even better passive you must have this never go without Preferred items These items gives you the last bonuses you need Phantom Dancer Now it's the time to upgrade your Zeal to this evil item, gives you everything you need to kill **** really fast Guardian Angel People would likely focus you but what if they kill you? The rest of your team starts to kill them one by one and then you rise from the dead and clean it all up with your lifesteal and attack speed you should have your hp back in few seconds Last Whisper People think armor counters you? with this item nothing really can counter you Bloodthirster You've killed a lot of people to get to this point? and of course you would like to increase your chances of winning, so why not give yourself some more attack damage and lifesteal by replacing your beloved Wriggle's Lantern with this badass Optional items Frozen Mallet You would like some hp? This is the item for you, it also increases your ganks by getting an Phage early on Atma's Impaler You got some nice hp thanks to Frozen Mallet then you want some damage this item is the item for you + it also gives you armor and crit Madred's Bloodrazor These people are stacking so much HP and i can't kill them? What do i do? The best solution is this perfect item, might give you an overdose in attack speed but hey Master Yi likes Banshee's Veil The reason for picking this item if for the magic resist and spell shield if you're getting stunned to death this can really help you when you decide to engage (but the shield breaks really easy) Maw of Malmortius This item is really a beast, it gives you tons of damage when you're dropping low and probably the most common reason for taking this item is because of the passive, if you find yourself getting instant bursted why ganking by etc a Veigar or Le'Blanc this can save your time really many time and combined with Meditate that Karthus can't hurt you much with his Requiem QuickSilver Sash If you didn't pick Cleanse this ability is a MUST! but even if you picked cleanse this can come in handy Zhonya's Hourglass Wierd item on Yi? yearh maybe but so many times you would like the enemy team to focus some other well here's your option it also gives you some decent armor and the ability power are not even that bad on yi since his Alpha Strike and Meditate are really good with AP The Black Cleaver If people haven't figured out that armor actually reduce's damage this item is way better than Last Whisper Wit's End You want some magic resist? yearh, but you still want attack speed? this is the solution the passive applies really fast because of your attack speed. Elixir of Agility Whenever you have the gold get one of these they always come in handy. Elixir of Fortitude Same reason as Elixir of Agility. Optional Boots Boots of Swiftness fastest boots i the game (in combat) can be useful for both chasing and escaping, some like them Ninja Tabi Those ad carries are really fed but i don't want to stack armor, now you don't, pick these boots and you're alright mercury's treads These can be used very well if the enemy team got lots of cc and your Cleanse or Quicksilver Sash can't handle it or if you just want some magic resist ;)

Main route

Thanks for reading my guide please comment and help me improve it :)