Master Yi is very strong melee fighter but his skill are all ability power. Master yi is very strong person in attack speed and very strong on his offense moves. Master Yi can also go lane in the mid, bottom and top. Master Yi is a very strong offensive person so he should be in front of the line.

The Runes that you'll need is the Greater Mark of Malice, Greater Glyph of Clarity, Greater Seal of Evasion and Greater Quint of Malice.

Greater Mark Of Malice because of his Critical Chance of Attack Speed and Strength.
Greater Glyph of Clarity because it will give you mana regen to help using your ability.
Greater Seal of Evasion to help Dodge most of the attack that comes at Master Yi.
Greater Quint of Malice to do more Critical Chance.

The Masteries that were used were 21-0-9
You can choose most Master Yi build in masteries by giving more of the Physical Attacks in Offense none for Defense By Increasing some of the Utility to help out.

The Items that were used were: Berserker's Greaves, Stark's Fervor, Phantom Dancer, The Bloodthirster, Infinity Edge and The Black Cleaver or The Frozen Mallet.

Aim to cheapen these items so that you'll be able to kill most champion in a few hits.
Start off with Boots of Speed and 3 health potion.

1.AlphaStrike
2.WujuStyle
3.AlphaStrike
4.Meditate
5.AlphaStrike
6.Highlander
7.AlphaStrike
8.WujuStyle
9.AlphaStrike
10.WujuStyle
11.Highlander
12.WujuStyle
13.WujuStyle
14.Meditate
15.Meditate
16.Highlander
17.Meditate
18.Meditate

Ghost: To Freely escape.
Exhaust: Slows Enemy down catch up to them and get a kill.
Flash: To Escape as well but goes through wall.

Hopefully this helps you and this is a very successful build.