Grimoire of the Dead

Oracle Text

1, T, Discard a card: Put a study counter on Grimoire of the Dead.

T, Remove three study counters from Grimoire of the Dead and sacrifice it: Put all creature cards from all graveyards onto the battlefield under your control. They're black Zombies in addition to their other colors and types.

Card Rulings

9/22/2011 “Creature cards” includes each card with the type creature, even if it has additional types, such as artifact.