Whisper, Demiurge of Thieves

Deathtouch, first strike
Whenever Whisper deals combat damage to a
player, that player mills twice that many cards.
At the beginning of your end step, choose target
noncreature, nonland card in an opponent's
graveyard that was put there from their library
this turn. You may cast that spell without paying
its mana value. Then exile it.