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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!