Feral Demoness

Flying
Whenever Feral Demoness attacks, hinder(Choose a creature with the greatest toughness from amongst creatures you don't control, put a -1/-1 counters on it.)
If a creature dealt damage this way would die this turn, Feral Demoness gets a +1/+1 counter and you gain X life, where X is how many -1/-1 counters were on that creature.