Abhorrent Overlord [Theros]

Set: Theros Type: Creature — Demon Rare Cost: {5}{B}{B} Flying When Abhorrent Overlord enters the battlefield, create a number of 1/1 black Harpy creature tokens with flying equal to your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.) At the beginning of your upkeep, sacrifice a creature.