UPDATED

First of all I would like to say,that this build is mainly for 3v3.As from my personal experience,yi is an easy target to kill in 5v5,and is usually the first target.

Pros

Burst dmg
Great chaser
Great pusher/farmer
Great at escaping,when slowed,by using your ulti

Cons

Low hp
Easy to die when stunned
Usually the first to be hit in ganks in 5v5

SKILLS

A nice passive for yi.Since yi has a lot of attack speed,this passive helps him a lot.Every 7 hits,your next hit will hit like 2 hits.

A great skill that damages the selected target and nearby random targets,but sets priority to attack enemy champions.It deals a good ammount of damage,basically you start your attack with this skill.

Yes,I believe it is.It is a ****py skill in my opinion which will only help you when you are the first target.It is interruptable,and does not do anything rather than wasting your enemies' time by a little.It has only saved me in limited situations.

A really GREAT skill.It boosts your AD by a lot(passive),while the active doubles it!So the passive grants you +35 AD,but the active grants you +70 in total.Ofc the passive is removed when active is enabled.

Your ulti.Not the best ulti,but it really fits greatly.It gives you Attack speed,a lot of movement speed and you cannot be slowed!
You ulti is recharged whenever you get a kill,or half recharged whenever you get an assist.So always use it in the right moment!

Your Style of Play

Whenever you see an enemy you will do the following:
Use ,followed by activating your ,followed by your ulti.Always attack the easiest target first,NOT TANKS,and focus on the same target as your teammates do.You will be the one getting the kill,probably.Avoid going first into a crowded fight,(2v2 or 3v3)when you're facing champions that can stun you or immobilize you(ex:Sion,taric,ryze,morgana,pantheon).The results will be you end up dead.

Items

Early Game

First of all,start off with your boots,they can really help you for a FB early game.Use your pot whenever you think it's the right moment.NEVER go rambo,let an other teammate go first.Try to get the last hit and kill the creeps as much as possible,the more gold you get,the better.Continue by buying your ,attack speed is what you need in early game.Your next item shall be Stark's Favor.This item is really great,as it not only increases your attack speed and Lifesteal,it also increases the attack speed and lifesteal of your allies!

Middle Game

Your next item shall be the ,the passive and the damage is great,while lifesteal is the thing making it better.The next item you might want to buy is or Phanthom Dancer.Either way,the combination is deadly.What makes it deadly is the passive of ,making your crits hit 250% instead of 200%.So buying both is essential,in order to increase your crit by a huge ammount.The damage,AS and dodge are also amazing.


Late Game

Well then,late game,so it's your last item.Since you got a lot of dmg,we should focus on our survivability.Getting is in my opinion,the most profitable item to get.It adds up both armor and MR that you need, and grants you a second chance when you die with its' passive.The truth is that sometimes,you might need to buy this before some other items,so the item sequence can also be like this:

---> ---> ---> ---> --->

Targets that you should be afraid of:

:His armor,combined with sunfire capes,his ulti,etc etc,is really deadly for you.
:He can take you out in a hurry.
:If he stacks up dodge,it's kind of impossible for you.
:No...You wouldn't like to go 1v1 versus her.
:He is really hard to kill,especially if he uses tanking items.
:A lot of damage,combined with his stun=dead.

Tips:

1.You can use in a creep nearby your enemy if you can't reach him,there's a high possibility of him being damaged.
2.Always have your passive charged early game!It makes a lot of difference going into fights with it,the double hit might make the difference.
3.Don't spend time using ...By hitting,not only will you damage your opponent a lot,but you will also be healed a lot,making it really hard for him to kill you.
Ofc, when having enemies like and you should always use
4.Never engage a fight first.Leave it to the others.
5.Don't be afraid to last hit creeps by using .

Comments are apreciated.