Aster, North's Bride

-X: Destroy target creature. You lose loyalty counters equal to its toughness.
-1: Until end of your opponent's next turn, Aster becomes a 6/1 black flying Vampire creature with indestructible. She is still a planeswalker.
0: Sacrifice a creature if you have one. Target opponent discards a card or sacrifices a creature (their choice).