Master Yi Build
Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
When I play Master Yi, depending on if the other team has a tank, I usually get Madred's Bloodrazor instead of Infinity Edge. I do this because if the tank gets Thornmail (which he probably is going to get) Infinity Edge will literally get you killed. Thornmail's passive makes it so that when you hit him 30% of the damage is dealt to you. Madred's Bloodrazor's passive makes it so that you deal 4% of the targets maximum health in MAGIC DAMAGE, most people don't realize that it's magic damage and not physical DPS. Now back to the build. Some people think it's dumb to get boots of speed in the beginning of the match but it actually almost ensures First Blood.
MID GAME: By now you should have Stark's Fervor which gives you insanely good life steal and attack speed for you AND your team, you are now a support/DPS. At this time you should have at least one of their turrets down, making it easy to chase with highlander and/or ghost. Master Yi in my opinion is the best for killing the guys that are about to recall by their turret because he can just highlander in and highlander out with getting hit by the turret only about 2 or 3 times.
Now when you play Master Yi there usually is no late game, you just end it too quick, especially with my build. My build ensures that you can chase without being ganked, be a little bit of a support for your team in group fights and just flat out own.