Where are AP Assassin Items?

I know already the AP assassin class is very small.

All these champs utilize basic AP mage items, but where are the Assassin items? All the AD assassins have really strong items for their class, and they dont rely on adc items most of the time.

I can agree Rabadons and voidstaff are the most important portions of an ap kit for max damage, but they dont offer much for ap assassins in utility. Like ad assassins, they need penetration, or, as of now, lethality. Shouldn't riot be fair to Ap assassins as well and give them this stat too? It makes the lives of this class much easier to do what they were meant to do: assassinate. Thats what riot wants to do with the assassin update anyway.

The movement speed is also something ad assassins get. Sure, there's ludens for ap, but its been used as a basic mage item and assassin-ish item that I only sometimes build on them for a little extra ms. I think there should be another item that gives magic pen as well as more utility that shows some love for this little group of guys.

IMO, my biggest candidate would be . All of these assassins use autos efficiently, and it offers potential burst more valuable to this class than most mages. Think about it: the only champs who are mages that really use this as a core item are and .

Proposed idea for Lich bane: I think this item can be reworked to gain ms when using a basic attack after casting an ability. "After casting an ability, the next basic attack will gain bonus damage based on ap and ad as well as giving a movement speed buff. For the next three seconds, the target has their magic resist reduced based on level" The ap on this item would probably be reduced to 60, giving bonus ms and magic pen along with the strong passive instead cdr and mana. IK, without mana the couldnt be in the build, so the proper item to replace it would be . I mean, the bonus damage based on ad never helped ap champs anyway. Revolver is much better for their build path. This would make for a much better item dedicated to this class that could be balanced and more useful to a whole class of champs as opposed to the few that lich bane already serves well.