Sigismund Dijkstra

Creatures you control but don't own are Rogues in addition to their other types.

Face-down creatures you control have
"{2}{u}{b}: Turn this creature face up. If you can't, exile it, then you may play the exiled card without paying its mana cost."

Whenever a Rogue you control deals combat damage to a player, cloak the top card of that player's library