This build starts of super dependant on your expunge for early game, but once you get the attack speed and what not, your expunge turns into a pretty useless factor. This is completely intentional though, the whole purpose of this is so you can pull off nice burst early game since you've got nice ap to boost that expunge, and attack speed to add stacks faster. But once you start getting that crit, and high attack speed, you will be an unstoppable force. Please Note Don't take wits end if there arent many heavy mana users on the enemy team.
In my option I believe Phantom dancers are too uncommonly used by twitches, but if you use this, it will open your eyes. Nice map control, Great crit, typically around 90%, and roughly 2100 attack speed.