Gravecrawler

When Gravecrawler attacks, if defending player
has less than 5 cards in their graveyard, they mill
1 card. Otherwise, create 1 1/1 black Skeleton
token with reach. If that player has 10 or more
cards in their graveyard, create 2 of those tokens instead. If they have 15 or more cards in their graveyard, create 3 of those tokens instead.
"A swarm so large your head will spin."