Bonehoard is a rare Artifact — Equipment card from Mirrodin Besieged (MBS), collector number 100. Current market price: $0.32 (foil $5.37), TCGplayer market prices via Scryfall.
Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.) Equipped creature gets +X/+X, where X is the number of creature cards in all graveyards. Equip {2}