Toxrill the Corrosive

“At the beginning of each end step, put a slime counter on each creature you don't control. <br>Creatures you don't control get -1/-1 for each slime counter on them. <br>Whenever a creature you don't control with a slime counter on it dies, creature a 1/1 black Slug creature token. <br>UB, Sacrifice a Slug: Draw a card.”