Evicerus, Eternal Ember

Flash, flying, haste
When Evicerus, Eternal Ember enters the battlefield, it deals X damage to up to X target creatures or Planeswalkers, where X, and its
power and toughness, is equal to the amount of
mana spent to cast it.
{x}{x}{r}{r}: You may cast Evicerus, Eternal Ember
from your graveyard or exile. X can't be 0.