Skeleton Colossus

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Skeleton Colossus gets -1/-1 for each card in your graveyard.
{3}{b}, Exile a creature card from your graveyard: Create a 1/1 black Skeleton creature token.
All the corpses killed by Yawgmoth mysteriously vanished on Urborg. Soon after, it appeared.