This is a Full Critical Build. Master Yi becomes high powerful on 1v1 and letal on team fight. Being able to kill fast and regenerates a good life with lifesteal.

For a good start you can do a Boots and 3 Health Potion. After 2 Phantom Dancer you can sell your Boots.

When you charge Bloodthirster your damage goes from 365 to 445. When you turn on the Wuju Style your damage goes to 480 . With your 283% Critical Damage your damage goes to 1350 with 100% chance. That will give you a 540 Lifesteal per hit (When the both The Bloodthirste are full charged)

Something on Master Yi that the most part of people don't know is that when he kills someone and has the Wuju Style on, he has both effects, passive and active, giving him more 35 Damage. It's always good after killing someone wait for the active effect finish before using it again; You will save mana and give more damage.

At late game you can switch your Boots for an Frozen Mallet to give you some health and slow on the target, making it harder to run from you and helpfull on giving more damage on a chase.

Pros:
Powerful when in close combat.
Hard to kill while hitting.

Cons:
Any disable can easily make you useless.
Low health