Normally what i do is rush rylai's crystal scepter for a mix of health and damage. Then i get mobility boots which help you roam to other lanes and pick up other kills. then i build into a lich bane to help with turret killing and more damage and mana. death cap will just boost your overall damage. next will be zhonias hourglass will give you some amour and the stasis effect, while giving more damage. then round out your build with another death cap if needed and your team needs more damage. sometimes i grab a Rod of ages in place of the last death cap if they have allot of bruisers. and if you are forced to stay in lane because your tower is being pushed, i go with sorcerers shoes instead of mobi boots.