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.
Updated the build as I've gotten more experience with it.
I've mainly gotten rid of a lot of the mana regen items/runes.
This is a build for a mid Corki that will carry the team. The vampiric scepter will help you stay in the lane early on, as will the heal, and ignite should net you an early kill or 2.
At lvl 11, start going to the far lanes to gank opponents & finish off enemy towers.
Don't hate on the build until you try it. ;)