Nim Deathmantle is a rare Artifact — Equipment card from Scars of Mirrodin (SOM), collector number 188. Current market price: $4.69 (foil $12.41), TCGplayer market prices via Scryfall.
Equipped creature gets +2/+2, has intimidate, and is a black Zombie. (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.) Whenever a nontoken creature is put into your graveyard from the battlefield, you may pay {4}. If you do, return that card to the battlefield and attach this Equipment to it. Equip {4}