Underworld Siege

Sacrifice any number of creatures. For each creature with power 3 or less sacrificed this way, create a 2/2 black Skeleton Warrior creature token with deathtouch. For each creature with power 4 or greater sacrificed this way, create a 6/6 black Demon creature token with flying and "At the beginning of your upkeep, this creature deals 1 damage to you."
This gives a whole new meaning to 'All hell's breaking loose'.