Nyxa, Fallen Adventurer

+1: Mill 2 cards, then create a 1/1 black Demon creature token with "When this creature dies, all players mill a card."
-X: Create X 1/1 black Demon creature tokens with "When this creature dies, all players mill a card."
-10: You gain an emblem with "Whenever a creature is put into a graveyard from anywhere, create a token that is a copy of that creature."