Uchbenbak, the Great Mistake is a uncommon Legendary Creature — Skeleton Horror card from The Lost Caverns of Ixalan (LCI), collector number 242. Current market price: $0.20 (foil $0.30), TCGplayer market prices via Scryfall.
Vigilance, menace Descend 8 — {4}{U}{B}: Return this card from your graveyard to the battlefield with a finality counter on it. Activate only if there are eight or more permanent cards in your graveyard and only as a sorcery. (If a creature with a finality counter on it would die, exile it instead.)