Wither, Crafted for Decay

: When a creature enters the battlefield, put a -1/-1 counter on it. If it is a black or white creature, put a loyalty counter on Wither.
-8: Wither becomes a 7/7 black demon creature with Vigilance, Flying, and Indestructable.
-X: Distribute X -1/-1 counters on creatures you don't control.