This Build works best mid lane, but can also work in other lanes as well.

Start off grabbing your items and heading to mid. Let the enemy push you almost to your tower, all while using your Q to last hit and poking as often as you can with your Q+W Combo. around level 4 when you see there low enough HP Flash in with your E and finish them off. repeat this as often as you want.

Once you get your Majai's, stacking it will be easy. By 20 Stacks along with your Archangels your full combo should be hitting rather hard. And your ultimate should more then supply for that left over health when they run.

With your Attack Damage items. Your Regular attack should be doing a far bit of damage too, Using it during your spell cooldowns will ensure the kill.

Late game its all about positioning. Stay in the back of your team throwing your Q+W as much as you can, when you see an opening flash in with E and take them out. Your Ultimate is on a very short cooldown and is almost almost up when needed, so try to never let anyone escape.

if you get into a large team fight that your team seems to be losing. Donlt be afraid throw your ultimate in and try to hit as many champions as possible. Your ultimate should do fair amount of damage that my give your team the advantage, as well as scaring the enemy team back some. Your ultimate is on a short cooldown, so it'll be back up with in no time.

And remember when your team wins to /T near the nexus ;)

Pros:
High damage output mid/late game.
Physical and Magical Damage.
Short Cooldown on all his spells.
Arcane Shift Can act as a great escape tool combined with ghost.

Cons:
Super Squishy.
If focused it wont take much to take down.
If you overextend in a team fight you have a high chance of dying.
Mana problems early game.