Hulxus Hex, Decay

Demons you control have Wither.
Hexes you control have "{g} {t}: Put a -1/-1
counter on target creature."
Bestow {4}{b}{g}
Enchanted creature gains Infect if it's a Demon. Otherwise, put a -1/-1 counter on it at the
beginning of your upkeep. When it dies, its controller gets an infect counter for each -1/-1
counter it had.