This build/guide is the way i play my Master Yi, im lvl 22 right now, my wins 102 and loses 92, almost play Yi all the time you might like this guide if you like critical situations...

I've done 3 tetra kills with this build...
When you're in battle aim for the squishy/lowhp guys with the "R" and "E", after slay that enemy clic "R" and "E" again and keep aiming for the lowest hp champ, and keep doing it till you die, or you kill everybody...

The runes selected are for a good start since you might have a lot of atck speed so you can slay minions faster at beggining and lvl up. As well you would be able to destroy turrets in 7~11 secs with "R" and "E" in a mid/late game.

The critical chance runes are for mid/late game where the critical strikes make the difference in battles...

You might need a good movement speed so you can get from one tower to another and to escape from losts battles.

The masteries selected are only for you to get a higher damage plus critical chance plus critical damage, you might need them on the go.

You need flash to escape from some battles or you can use it to slain an enemy near a tower then flash you out. The flash spell could be changed for "TELEPORT" so you can get in to battles more often or just to save your turrets for being destroyed.

Ghost spell would be cool to use if you need to really escape, as well since Master Yi run like hell with the masteries and this spell you would be out of combat easily to go "B" or support any other place...

Thank you for reviewing this build, if you have time to try a game with this build and provide feedback i would appreciate that, please vote and comment =D...

Nice day ^^...