Grimoire of the Dead is a mythic Legendary Artifact — Book card from The List (PLST), collector number ISD-226. Current market price: $1.82, TCGplayer market prices via Scryfall.
{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.