This is my first build of Master Yi and my first build on this website, so if you please, please don't say rude comments on my build, it's my first, thank you !!

For the runes, Greater Mark of Fortitude is good for Master Yi because Master Yi gets pretty low health when he's level 18.

Greater Mark of Intellect is also good for Master Yi because he uses way too much mana and these 9 runes will help him with his mana.

Greater Mark of Furor is also good for Master Yi because the critical damage will help Master Yi serve more damage to an enemy/opponent.

Greater Quintessence of Strength is also good for Master Yi because he doesn't really have a good chance with critical strike so he'll need these runes for higher damage.

Offense
Deadliness - Good because more critical chance for Master Yi.
Cripple - Good because when Master Yi uses his Exhaust spell it will reduce the target's armor and magic resistance for Master Yi to attack and kill easily.
Sorcery - Good because Master Yi's cooldowns are pretty long so this Mastery will help Master Yi with his cooldown troubles.
Alacrity - Good because Master Yi's attack rate will be higher and will be easier to kill enemies.
Sunder - Good because when Master Yi attacks the target's armor will reduce making the target easier to kill.

Defense

Resistance - Good because Master Yi will take less damage form AP characters because of magic resistance.
Hardiness - Good because Master Yi's armor will be raised making the enemy harder to kill Master Yi.
Strength of Spirit - Good because Master Yi's health will regain from his maximum mana.
Evasion - Good because Master Yi will dodge more attacks making him live.
Harden Skin - Good because Master Yi will block an enemy's physical attack.

Utility

Perseverence - Good because Master Yi's health and mana will regain faster.
Haste - Good because when Master Yi uses his Ghost spell he will run more faster and it will last a wee bit longer.
Awareness - Good because Master Yi's experience will increase making him level up faster.
Expanded Mind - Good because Master Yi's mana will regain faster from his maximum mana.
Meditation - Good because Master Yi's mana regain will become faster.

Start off with the Doran's Ring and a health potion, I don't know what this does but I've seen it in a lot of Master Yi builds.
Then get the Berserker's Greaves for faster attack.
Then get the Youmuu's Ghostblade for using for faster movement and really fast attack attack speed.
Then get the Phantom Dancer for some fast attack speed, high critical strike, and some movement speed.
Then get the Malady for some ability power and some really fast attack speed.
Then get the Bloodthirster for some attack damage, lifesteal, bonus is 1 physical damage and .25% per kill, if you die bonuses are resetted.
Then get the Last Whisper for some attack damage.

Maxing Wuju Style is a good idea because when you use it when attacking an enemy you will kill him easily.

Exhaust is great for slowing and Ghost is great for running away or for chasing people.

Use Highlander, then use Wuju Style, then use Youmuu's Ghostblade, then use Ghost, then use Exhaust, then use Alpha Strike, then get a 5, or 4, or 3, or 2 kill in a row.

This build is made by WujuYii, thanks for reading, haha, got questions? Add me at justinv1p@hotmail.com.