Xæl, Hellfire Archivist

This spell costs {1} less to cast for each creature card
in opponents' graveyards.

Xæl's toughness is equal to the number of creature cards in your opponents’ graveyards.

Whenever Xæl enters the battlefield or attacks,
exile up to one creature card from each opponent's graveyard. For each card exiled this way, create a token that's a copy of it, except it's a black Zombie.