Char description.

Master Yi is a fast char that can diliver great amount of damage in short period of time. He is one of the greatest (if not the best) carry/pusher/farmer ingame.
Apart of great dps, huge criticals, great atack speed he has a superb chasing mechanism as well as it can be used as superb escape mechanism.


Pros and Cons

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 Ulti 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 oponent. Good for harrasment.
Extremaly usefull in early game when every % of hp matters, as well as in late game when you diliver 1k crits (double 1k crit? shiny?).


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

In my playstyle, this is my initiate skill, as well as escape mechanism (but this is very mob dependant escape mechanism)
Basicly you "rush" through 4 targets (mobs) and land a final blow on the targeted champion/mob spawning near him. You cant hit same person multiple times. You cant jump back to char that was already "touched", so catching 2 heroes alone wont mean you hit both of em 2 times, the spell will break after 2 jumps. This skill ignores your melee damage, damage is magical and gets lowered by magic resistance.


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

Very underestimated skill. In late game it can be whole diference between going back to base or stay in lane and push another tower.
It might be good idea to take a single point in in in early game if you are getting too much harras damage.
Not much usefull in late game since you will regain more hp and faster and more efficient by just farming mobs with lifesteal.


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

Your primary skill. Passivly increases your swing melee damage. On Use you get up to +70 damage. Cannot be boosted by anything. Great skill early game. Scales with Double Strike.


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

Your Ulti and MOST IMPORTANT skill. This is what makes you a lethal killing ********* machine. Most of the way of usage is to chace fleeing enemies, but it can be either as offensive as defensive ability. It allows you to catch absolutly everything in no time. It allows you to safely flee without any fear of getting slowed (don't you love the red info "Cannot be slowed" apearing above your fleeing ***?)
Another great thing... after you chase down and rip your oponent apart while this skill is active... you can do it again on another champion... coz it refreses all your cooldows with no exeption of the ulti itself... so have fun with those double/tripple/multi/ultra-kills.


Skill usage

More or less your dps should look like this:
Alpha Strike on a hero -> Enable Wuju Style -> slap slap slap dead - profit!
or
Alpha Strike on a hero -> Enable Wuju Style -> slap slap o_O You want to flee? Go ahead -> Enable Highlander -> slap slap slap dead :) cooldows refreshed hmmm witch one will be next...
when you are sure of scoring a kill but you need to do it fast:
Alpha Strike on a hero -> Enable Wuju Style -> Enable Highlander -> slap slap slap dead :) cooldows refreshed hmmm witch one will be next... (watch your mana pool if you dont have blue buff)
In worst scenarios:
Alpha Strike on a hero -> Enable Wuju Style -> slap slap, whops he is beating my *** off... -> Enable Highlander and GTFO of there :)


Runes

Greater Mark of Desolation
Greater Quintessence of Desolation

Marks and Quintessences for ArP. Atm the biggest damage wise boost stat ingame. Makes HUGE diference in early game. With your highest ingame AD base, you will be no match in most cases paired with those babies.

Greater Seal of Evasion

Great addition to Phantom Dancer and Numb mastery. Saved my *** soooo many times. Also great runes for tanks and all other physical champions. Costy (820IP each) but totaly worth it. If you dont have AP runes it will be a good sollution for squishy casters as well.

Greater Glyph of Furor

I prefer crit damage over crit chance since it's more endgame'ish. Your crit due to PD + IE will be high enaugh to maintain this. I dont feel any urge to get % crit for early game since i depend on double strike and AS from 2 early game items (3 if you count boots).


Items


CORE




You should start with picking up a Boots of Speed, 2x Health Potion and 1x Mana Potion, and head for a lane.
With your huge damage it shouldn't be much of a problem last hitting mobs. Try to harras a bit with Alpha strike+double strike -> run away combo. Stack up hits for double strike buff, enable Wuju, Alpha to enemy, hit once and run away (or kill :P but dont be greedy).
You should have gold for Berserker's Greaves SUPER fast. Get them. (might be forced to buy additional 2x Health Potion. You shouldn't be afraid of getting harrased (but not nuked!) so use those pots :). Dont get too coky tho.
On getting lvl 6 you should be able to score a kill or double kill with 1 ultimate. This full skill combo will probably drain you from mana quite much, you can get back to base to replenish and to get Recurve Bow. Always try to get the bow before lifesteal. Even if you have to go to jungle to kill fiew mobs. After you get this, you should get a Vampiric Scepter or completing Stark's Fervor fully.

!!!WARNING!!!
If the early game situation is not going great and you cant buy Recurve Bow fast enaugh i HIGHLY suggest going for Zeal than get Emblem of Valour to finaly complete Stark's Fervor and than complete Phantom Dancer as specified below.
!!!WARNING!!!

Why focus so much on AS 1st? Coz we count on getting as many double strikes as possible. Crit is nice but it is a random thing in early game, and double strikes are sure. Make use of em. Your power with wuju style will be enaugh to take down even tanks.
Than you can jungle a bit to get red and blue buff, gank once or twice and get Zeal asap. This will give you that AS/Crit/MS boost you realy need.
You dont have to worry about your damage still so after fiew kills you should be able to complete Phantom Dancer with ease.
Now comes the "hard" part. Wuju will be maxed now, and you will see your damage dropping. We need some damage.
By this moment there is 1 rule you have to follow:
ALWAYS BE KILLIN' SOMETHING!
You have to be farming. Constantly. If you are not on a lane, pushing creeps/towers or ganking you should be farming in jungle, rebuffing. You have to always be on the move killing something/someone. If you stop you will get a huge gap in cash flow. Remember you are very item dependant, you need getting items constantly constantly constantly.
Now it is the time to gather cash for Infinity Edge. After you get this item... it's a GG already. Taking whole teams and turrets under 10s will be no problem. Push and farm farm farm.
If the game is still running, get another Vampiric Scepter and swap it into The Bloodthirster.

You have your 1 slot open at this point. If the game is still running you can pick:


BONUS

Tiamat - for pushing mob waves in notime (helps alot if you are the one that takes care of BIG waves of mobs with super creeps.
Frozen Mallet - If you want to slow down your enemies and hit them more frequently.
The Black Cleaver - If you are facing realy tough tankers or heavy armored teams, this will rip them apart.
Guardian Angel - Imho the best pick for ranked games as last (6th) item.
In VERY VERY late game you can swap boots for:
Madred's Bloodrazor


Situational items:

Banshee's Veil - For heavy caster teams.
Last Whisper - Item for lategame armor penetration for ppl that face heavy tanky teams. Get this only if you already got Infinity Edge.
Force of Nature - for Heavy AoE teams (Fiddlesticks + Karthus combos for example).