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This is the build I always use with Master Yi, and I just rape people even full blown tankers.


Pros
+Great damage
+Great atack speed
+Superb chaser
+Great escape mechanism
+Superb pusher/carry/farmer
+Easy to play
+Good harraser

Cons
-Squishy early game
-Vurneable to disables
-Easy to harras (Melee)
-Low HP pool
-After using Ult on a gank that is not working out, he has no way of fleeing from battle.


Skills
Double Strike - Master Yi strikes twice every 7th attack.

Passive that every 7th can take out great amount of oponent HP pool without any problem. Scales with your accual damage (also with enhanced by Wuju Style skill).
Timing it will be a nice thing now. Remember that when counter hits 6, this means your next atack will deal 2x damage. It means you can Alphastrike and double damage opponent.
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 100/150/200/250/300 (+1 per ability power) magic damage to each enemy with a 20/30/40/50/60% chance to deal 400 bonus magic damage to minions.
Cooldown - 18/16/14/12/10 seconds
Cost - 80/90/100/110/120 Mana
Range - 600

Great for harrasing players so much. I love it, also great for farming on minions, cause i can take out a whole group of minions with just using this once. Also when you are very sure you can kill a champion next to their turret and get away, using this skill can land you a kill before a turret hits you.
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 140/280/420/560/700 (+1.65 per ability power) health over 5 seconds. While channeling, Master Yi gains 100/150/200/250/300 armor and magic resistance.
Cooldown - 35 seconds
Cost - 70/85/100/115/130 Mana
Range - Self

I say this is a very good skill, for late game this could be the difference of going back to base and heal, or being able to stay in the lane and destroyed by a turret without worry about being killed in a hit or two.
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 by 15/20/25/30/35.
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.
Cooldown - 25 seconds
Cost - 40 Mana
Range - Self

A really good skill when killing a champion, or even a turret or whatever. After your first skill Alpha Strike use this and you will do so much damage, or with your ult and you can take down champions, and turrets, and the nexus. It also stacks with the double strike passive. :D
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 by 40% and Attack Speed by 40/60/80%, and he becomes immune to all slowing effects for 6/9/12 seconds. Additionally, killing a champion refreshes all of Master Yi's cooldowns, and scoring an assist reduce the cooldowns by half.
Cooldown - 75 seconds
Cost - 120/120/120 Mana
Range - Self

OMG Master Yi's Ult is so helpful in killing anything, or just running away, this skill could be the difference of getting kills or living. When activated you gain crazy attack speed, combine that with your wuju style and it will be over. Or you can use it to run away, cause when activated you are immune to slows and stuns for 8 seconds.

Skills
Alpha strike -> Exhaust -> Wuju style -> Ult = TOTAL OWNAGE! (:
Ghost -> Ult = Im McHammer cant touch this. :D


Good teammates:

Disablers:TaricSionAmumu

Slowers:NasusNunuSwainAshe

Taunters:RammusShen

Ofc Supporters:BlitzcrankLuxMorgana

Worst enemies:

Disablers:TeemoHeimerdinger

Heavy Range (Mostly Spellcasters):MalzaharRyzeVeigar

Thanks thats all I'll post a game with my score when I get the time, please rate and comment. <3