Wendigo of Hollowhenge

Sacrifice four creatures: Target opponent exiles the top four cards of their library. You may play cards exiled this way. Use this ability only once per turn as a sorcery.
{b}{g}{u}, {t}: Exile up to X cards from target player's graveyard, where X is the number of cards that player has exiled. Create X 0/1 black Human creature tokens.