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.
This is a mid/late game build that will make you opponent run away when they see you.
The build itself is based on raw damage and attack speed with some armor penetration so that you can do even more damage to tanks and other heavy armored champions.
The runes is more or less based on early game with some focus on survive so you don't get gimped early in the game. The armor penetration runes is nice early game for the extra damage you'll deal.