My items for the game are basically built on that AP poke and Mana to not take out of it. My starting items are Boots and 3 pots allowing me to stay in lane if i take some damage, or out speed their jungler if they come to gank. My First Back Items are 2 wards and a Blasting Wand. This allows me to dodge their ganks by seeing when they are coming. I also use the Wand to give me that early poke. My Core Items are Lich Bane, Rod of Ages, Rylai's Crystal Scepter, and Rabadons DeathCap. Lich Bane allows to to poke hard and gives me the mana to do that. The Rod of Ages is used for me taking damage while giving me that AP to beat them in the meantime. The Rylai's gives me health and some AP as well as a slow. The Rabadons allows me to have amazing AP late game. What did I leave out? The Abyssal Scepter or Zhonya's Hourglass. If you are facing an AP based team then build Abyssal, If they are AD based team then build Hourglass.