Asyntha, Courier of Fate

Flying
Prowess (Whenever you cast a noncreature spell,
this creature gets +1/+1 until end of turn.)
Whenever Asyntha, Courier of Fate attacks,
target opponent chooses a nonland card type,
then reveal the top card of your library. If it is
the chosen type, you may cast it without paying
its mana cost. Otherwise, put it on the bottom
of your library.