X, Mystery Racer - Unknown Event

When X enters, you may put it into target opponent's hand. If you do, as long as it remains in their hand, that player can't cast X and they play with their hand revealed.

During your turn while X is in an opponent's hand, you may activate abilities of nonland permanents opponents control. If you activate the crew or saddle ability of a permanent this way, gain control of it until end of turn. Untap it. It gains haste until end of turn.