Cthulu, Ruin-Bringer

Menace
As an additional cost to cast this card, sacrifice X creatures, and add X -1/-1 counters to creatures an opponent controls.
Terrify {b}{b}{u}: Target creature an opponent controls receives -1/-1 and is unable to block until end of turn.
Cthulu, Eldritch Horror gains +X/+X where X is the number of -1/-1 counters on creatures your opponents control.