I've also thought about a reverse sage/non trashing saboteur attack. The problem, as you brought up in another thread, the fact that it can hit a Duchy or Province and actually help the opponent. The shuffling may be too much to ask of an attack
I am putting the following card in my set:
Archer
Action/Attack - $5
Each player (including you) reveals cards from his deck until he reveals one costing $3 or more. He either discards it or puts it back; you choose. He discards the other revealed cards.
+3 Cards
So other than the fortune teller/reverse sage attack, it's also a stronger smithy. If you reveal a victory card or a dead action card, then it's basically +4 cards.
Is it too good early on?
EDIT: Didn't notice the "shuffle back in" effect.