This build is only viable if your a decent player, and you know how to help your team. That being said this build will also roflstomp your opponents when used right, so sre you ready for some hard, fun, roflstomping?

Magic pen. marks for early game roflstomping, mana seals so u can roflstomp more early game and ap glyphs for even more roflstomping early game. The health quintessence's for some survivability to roflstomp longer!

The usual ap carry masteries, the best i find.

Start with a dorans ring for the survivability, ap and mana regen. it benifits you alot early game. First time back buy first rank boots and catalyst for survivability. Second time back u should finish ROA and Sorcerers boots because you should have enough if you followed my build correct. From then on save up for needlessly large rod and finish rabadons deathcap asap. then build an abyssal scepter for the mp, ap and mr, it helps. Next build Zhonya's hourglass, its a ap carries best friend, use when you enter a team fight because they will be like squishy dangerous caster, RAPE HER!!!! but with the hourglass you survive and then unload your combo for massive anhialation while there stuff is on cooldown and your just fine. Last but least build a rylai's for the passive and nice boost of health.

Start with disintegrate because its your main farming tool. Follow it with incinerate as it is a main part of your combo. At lvl 3 you should get molten shield as it does protect you and builds towards your passive, from then on alternate between your q and w for most dmg during during your laning and as an obvious note upgrade your ult when available.

Flash is a must because it not only allows for a good get out of fail free button but also a good surprise stun combo. Ignite allow for a guarantee first blood kill or at least first mid kill which helps you win mid and if played right a team win! You could go with others but i tried numerous and this is the best but your decision.

Pros:
great burst
farming beast
you can drop ppl fast

Cons:
Somewhat squishy early game
if not played right = YOU get roflstomped
cant do it all to save your team

Whenever you enter a battle make sure your stun is up or else ganking is useless if you cant get your **** on them. In general have your stun up so you can use it for team fights when you drop tibbers to aoe stun them!