Dauthi Voidwalker

Shadow(This creature can block or be blocked by only creatures with shadow.)

If a card would be put into an opponent's graveyard from anywhere,
instead exile it with a void counter on it.
{t},Sacrifice Dauthi Voidwalker:
Choose an exiled card an opponent owns with a void counter on it.
You may play it this turn without paying its mana cost.