5/1/2012 :

Changed summary
Added gameplay chapter & runes chapter & masteries chapter
Posted a picture made by me in introduction chapter
Made some small changes

4/27/2012 :

Created guide : )

First you should get , then , then . After you get put 1 point in then 1 point in and at lvl 6 get the . After that you should max then (these are your main skills), after maxing them you may max and then .
So this should be the order :
Q,E,W,Q,E,R,Q,E,Q,E,Q,E,W,W,R,W,W,R .
And by their importance during gameplay this is the order :
> > > .

You will need some speed in order to run from lane to lane . And don't forget that attack speed is always welcome when we talk about Master Yi .

I don't see this item on much guides but belive me this item is nothing but great for Master Yi even if you get only an assist it still gives you +5 damage . Maybe you won't really feel it's effects in early game but in late game you will be a power house with this one . This is one of the items that will make your early game influence your late game .

This item is a must have for Master Yi, the attack speed and critical chance will make minion waves much easier to kill, and including the movement speed it will help you in chasing down fleeing players .

I think everybody knows why you should get this item. Master Yi is classified as a DPS champion and getting this will make you a very big threat for the enemy team .Usually after getting this item you won't need much more, in my case this is the point where the game ends.

If the game goes one you will need to get some more power and 2 x phantom dancer is the way to go since you should now be dealing a really large amount of damage with Sword of the Occult and Infinity Edge.

Usually I don't get to buy this item, but it may happen that a game will go this far and you will need this to help you keep up with the enemy team .

Ignite is good in early game, before having ultimate you won't be able to use Master Yi's true chasing power so you might really need this .
Teleport is needed, it is best to get as fast as possible back to your lane after recalling/ dying.

Alternative

And alternative would be heal since Master Yi is a squishy champion.

For the masteries you should have 21/0/9 . What do you get? A solid increase to Physical DPS, an experience advantage, and increased Neutral Buff durations.

ALPHA STRIKE

This is the only skill of Master Yi that deals damage to an enemy actually, the others are buffs for increasing attack damage/speed , movement speed, health .
This is great for last hitting minions, since it has a chance to deal extra damage to them .
Also using this in combination with Wuju Style should be your main weapon . Right after casting this on a champion activate Wuju Style and start hitting him, this will deal lots of damage.

MEDITATE

This skill is not that important in this build . BUT IT IS NOT USELESS . I suggest learning this ability at level 3 because it will help you stay longer in lane and whenever you are being chased and you are low on hp you can use this ( it gives you lots of armor and magic resistance) and hope for your partner to kill the chaser .

WUJU STYLE

This skill will help you alot during the game, besides the Alpha Strike - Wuju Style combination you can always activate this when attacking a tower, if you can activate Highlander too it will be very good because this is the combination that makes Master Yi a great tower pusher.
Try to have Wuju Style on whenever you are in a fight .

HIGHLANDER

This skill makes alot of people call Master Yi "overpowered" . Actually yes, it is a very good skill whenever you need to chase somebody or when you want to escape from a fight but, you can not call him overpowered just for this .

Knowing how to play Master Yi is knowing when to enter in a battle.

_______________________________________Early Game____________________________________

Get your Dagger and go in either bot or top lane.In early game you should be killing as much minions as you can . If the enemy team has a ranged champion in the same lane as you, you must stay near your tower, and let them come at you and usually use alpha strrike on minions, eventually the enemy champion may make a mistake and try to attack you, at that moment you should alpha strike on him in order to take some hp but I don't suggest trying to chase him since in early game it will be hard for you to escape if they have any kind of cc .
If they have no ranged champion then you and your partner should concentrate on the squishiest enemy . If he has got any kind of cc then you are lucky .
Try to stay in your lane till you get 915 gold, then push the lane a little bit and go back and grab Berserker's Greaves and Long Sword and get back to your lane as fast as possible . Now you must try to get as much gold as possible as fast as possible, because you have to get Sword of the Occult immediately. It will be better if you get it earlier because you will start earning stacks earlier and you will reach 20 stacks (if possible) faster.


__________________________________________Mid Game___________________________________
Considering mid game is after level six you should now be runing between lanes and look for kill opportunities. Since you now have ultimate you can chase champions so you are efficient at ganking . For a gank you must use the Alpha Strike- Wuju Style combination and in case you didn't finish the enemy with that chase him using ulti . You should get Phantom Dancer by now. After geting Phantom Dancer you will feel like the game became much faster (or at least I feel that personaly) .
Now it may seem a little hard for you to get Infinity Edge but if you didn't feed the enemy team, avoided dying and made some kills, or even assists Sword of the Occult will help you in killing enemy team much easier. Try to gank as much as possible .


________________________________________ Late Game____________________________________

Now you and your team should stay always together . Don't forget that you can crush towers very fast using Wuju Style- Highlander combination so try to clear all the towers of enemy team. Having both Infinity Edge & & at least 12 stacks from Sword of the Occult should make you a real power house. In teamfights you should stay back at first, you must never initiate a battle, if you do you will get killed. Knowing to play Master Yi means knowing when to enter in a battle. If the game goes on follow the item build list and always stay with your team, kill dragon, kill baron, DESTROY ALL THE TOWERS, do everything that can give you an advantage.