Skittering Consumption

Eternalize {4}{b}{b} ({4}{b}{b}, Exile this card from
your graveyard: Create a token that's a copy of it,
except it's a 4/4 black Zombie with no mana cost. Eternalize only as a sorcery.)
Once each turn, when a creature you control
with mana value 2 or less attacks, you may put
X -1/-1 counters on target creature defending
player controls, where X is the power of the attacking creature.