Vilsina, Wishshaper

{t}: When you cast your next instant or sorcery
spell, that spell becomes a creature in addition to
its other types. Put that card onto the battlefield
face-down as it resolves, it becomes a green
Wishborn creature with power and toughness
equal to the spell's mana value.
Whenever a Wishborn creature you control dies,
exile it, then reveal a creature card you own from outside the game with mana value equal to the
exiled card's and put it into your hand.