ok now i just want to clear one thing. That master yi early game is not a god like ok so you have to play carefully.Ask your team mate in the champion pick to gank bot the quicker possible.When the game start click on P and quick buy boots of speed 2 health pot ant 1 mana pots. And run in the bot bush. Take your q when the other team come attack it if they start to focus you use your q on someone.After the gank and when minion are spawming take the top lane solo. Move all the time use your q on a minion very close of the ennemy and back up just for low his life and FARM FARM FARM. Us build are very very costy. So we have to farm and to start carefully but take kill when you can. When you think you can kill it use your q on it and after spawn your e and attaack it when you know that with your exhaust he can't go away or kill you spawn it. After 4 or five your lvl 7-8 it's there your coming to just kill every body just spawn your q on the champion after use your E and R or just spawn your E and R. But assure your self to kill the champion when your R is on becaus that refreshes all of your cooldown.My build is on crit damage and lifesteal. I know that we have no survivability but us survivability is us lifesteal that can just save us on a 1v3 and win it. At the end we have like 75% of lifesteal of a bunch of damage. It's like that I play it full offense rune, masteries and gameplay.When a character is made for offense I make all to just owned evey body.I have game with this build of 42-1-3 31-0-2 and many more.TEST IT AND comment it plz thanks you ;) ohh and the only thing I can change is a bloodthirster for a last whisper if the other team stack armor!!