When you get into the game, buy two Faerie Charms. This will help in lane by allowing you to use your Q (Baleful Strike) to farm more. (Since with each minion kill on your Q you get an additional Ability Power). In lane, play extremely passively, only attacking minions close enough to you. When you have about 60 or 70 AP, start harassing the enemy champion. When they're low enough, use your full combo (Stun, W, R, Q) to finish them off. Gank the other lanes whenever possible.

Basically, stay out of the fight, stun as much as you can, and get kills using your Q or ult. Use W for additional damage, but don't expect to get many kills with it.

As in the first chapter, start with two Faerie Charms and three Health Pots. Later, build one Faerie Charm into a Philosopher's Stone and grab a Kage's Lucky Pick. If you have enough money, sell the other Faerie Charm and buy Boots of Speed. Build the Kage's Lucky Pick into a Deathfire Grasp (as this is a key item in your combo). Then, build the Philosopher's Stone into Shurelya's to help chase down enemy players. Grab Sorcerer's Shoes and then work on a Deathcap. Once you've finished your Deathcap, get either Rylai's or Will of The Ancient's depending on how much you feel you need health.