Grim Reaper, Lethal Legionnaire is a uncommon Legendary Creature — Human Villain card from Marvel Super Heroes (MSH), collector number 98. Current market price: $0.15 (foil $0.26), TCGplayer market prices via Scryfall.
Whenever Grim Reaper attacks, you may pay {3}{B}. When you do, return target creature card from your graveyard to the battlefield tapped and attacking with a finality counter on it. (If a creature with a finality counter on it would die, exile it instead.)