Undeads' Chosen

{t}: Sacrifice a creature: Search your library for a creature card and exile it. At the beginning of your next upkeep, put that card into your graveyard. Activate this ability only as a sorcery.
{4}{b}{b},{t}: Return a creature card from your graveyard to the battlefield. It is a Zombie in addition to its other types.
"Hear us. Save us. Join us."