I personally think Master Yi is the most overpowered carry in the whole game it is my opinion. Because he is all about attack speed and is super strong. This guide may not be good but i use it and i too not bad during games. So enjoy

I use Greater Mark of Strength because it gives me more bonus damage in the beginning of the game.

I then use Greater Seal of Alacrity for some more attack speed than usual to kill people more faster and to become stronger.

Then i use the Greater Glyph of Malice for some extra Crit chance for more damage and some lucky crits for the kill.

I use the Greater Quintessence of Malice for more crit chance and a bigger chance for a lucky killing blow.

I go with attack speed and attack damage i get life steal from the Bloodthirster, Attack speed, Crit chance, and movement speed from the Phantom Dancer, Sword Of The Divine for some awesome bonus attack speed, Boots of Swiftness for some extra speed, the Infinity edge for some awesome damage and critical damage and critical chance, and Black Cleaver for damage and reduce their armor to do more damage

For summoner Spells i usually take Flash and Ignite, I use flash to get out of teamfights but i know u guys may say that i have Highlander but i may be stuck with a person who can slow u down and you can just flash out of the corner in to a jungle route. Ignite is for when i did enough damage but i cant reach because of the turret, Ignite can damage them if you cant reach them and kill them with that certain summoner spell