Contract of Infiltration

Target nonlegendary assassin creature you control
gains shadow and "Whenever this creature
deals damage to a player, look at his or her
hand. You choose a nonland card from it.
That player exiles that card. As long as that card
remains exiled, you may cast that card, and you
may spend mana as though it were mana of any
type to cast it." until end of turn.
"House Driden has become an unknown quantity. Infiltrate and confiscate any dangerous information"