Sup guys! This is my first build here on mobafire.com! Now this is my first, but it is also the best! This build allows you to wipe out enemies with damage like none other, AND lightning quick speed. This is not a complete guide but I will let you know what you need to know!

Pros:

Extreme damage!
Very fast movement speed
You will be a force to be reckoned with!
If fed, the enemy team has NO chance.

Cons:

You are not a god sadly :(
Can easily be countered by an enemy team with fed tanks.
You are godly only late game.
CC will destroy you

VERY IMPORTANT Master Yi is EXTREMELY item dependent. I chose to go down the AD path because you have more damage over a steady course, while AP Yi only has Alpha Strike and can Meditate tank. This item purchase order is pretty straight-forward. If you are fed try to get both your Zeals before rushing an Infinity Edge. I would substitute the 2nd Bloodthirster with a Warmog's or a Force of Nature if the defense is needed.

OKAY so team fights should be very simple for AD Yi.

1. LET YOUR TEAM MATES ENGAGE FIRST
The most important thing! If you go in first, they will target you and well, a dead Master Yi isn't a good one :l

2. AIM FOR THE SQUISHIES!!
When you kill squishies while highlander is up, it gives you more firepower and your team mates the upper hand!

3.GANK ONLY WHEN YOU KNOW YOU WILL GET THE KILL
Example: Your teammate left mid WIDE open for enemy attack. Enemy Ashe decides to destroy your middle tower and keep pushing. Perfect chance! Come up from the river Pop highlander then Wuju Style and Alpha strike once then BAM. by the time she gets to her destroyed turret she is DEAD!!!

Ok, so my choice for runes. Seal of Aclarity x9 The faster Master Yi attacks the more criticals and tyhe more damage he can put out. Simple right? Glyph of Vigor x9 Master Yi is very good at sustaining in a lane, even if he is a bit mana intensive.
Mark of Fortitude A little survivability is always good. Especially because Master Yi already puts up alot of damage. Quintessence of Strength This tiny bit of attack damage will give you the upper-hand against other Master Yi's and, of course, will give you more damage overall.

My masteries are a bit odd but I find them necessary. I went 21/9/0.Unlike other carries, Master Yi's abilities ALL scale depending on ability power. So I find that that tiny boost in AP is important, but you could always go for full attack damage and put that 1 first tier point into Summoner's Wrath. That little bit of health from the points in the defense tree really works out. Trust me.

The Skill Sequence is different depending on what build you are using. But with my build, Meditate won't be of much use. I get 1 point in meditate for every 2 points in Alpha Strike and Wuju Style. I personally try to get Wuju to 5 before Anything. Except my ultimate of course.

I used to think Ghost was WAAAAY better than Flash. But then I starting using Flash and I found that Flash can Help you get that last hit on a running Teemo, or maybe get away from a turret that you just dove into. Flash is the way to go. Also Ingnite is a very important skill early game considering you can't turret dive. Also it can help you get that 1 kill you need to get the gold nescessary to get your Inifinity Edge.

This took me very long to write. Through much procrastination and hours of work, here is my god awfully written guide. I hope you own face as Yi! :D

Credits: Written guide - ME
Item Guide Idea - A youtube comment + my inspiration.