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.
What you want is to start with a Doran's Blade. Lane for a bit until you have enough to get another Doran's Blade and Boots. Start building a Sheen ASAP, then a Phage, then into a Trinity Force. Next, get Ionian Boots of Lucidity, then into a Recurve Bow, Pickaxe, then Madred's Bloodrazor. From here on out, you're basically unstoppable. Longer duration into the game, you build a Blood Thirster, Infinity Edge, and whatever you want as the last item. I picked Guardian Angel because most people will start to focus you and for survivability.
Remember to farm a bit at first, then start to harass and own. Usually mid lane works perfectly for this build. THANKS!