I'd take flat mana regen instead of per. level. It only benefits you early game, and when it's early, what use has the per. level ones? :)

Doran's ring is your start item, you'll buy it when the game starts.
You can replace Doran's ring with Bashee's during mid/late game or when the opponent has alot of magic resistance go for Void staff, in that case you don't have to replace Lich bane.

I've seen you play with it, so i've seen it works, build seems solid. What would you suggest to replace doran's ring for (if ur raging with tons of kills / playing with twisted fate) when gold seems to roll in very fast?

And why put a point @ flash in masteries when you dont use it?