Diabolos, Abyssal King

Flying, trample, menace, ward{4}
Diabolos, Abyssal King can't be sacrificed.
Whenever you sacrifice a creature with a mana
value of eight or more, while Diabolos, is in your
hand or graveyard you may put it onto the
battlefield without paying it's mana cost.
sacrifice one creature: target opponent
discards one.