Ishlak, Inventor of Disease

Origin (as long as Ishlak, Inventor of Diease is in your hand or command zone, creatures cannot be sacrificed by abilities, instants, or sorceries, except as a cost)
{b}: Target creature gets -X/-X until end of turn.
{b}{t}: Put X -1/-1 counters on target creature.
{b}{ut}: Target player that has not been targeted by this ability this turn sacrifices X creatures.