Archfiend of Despair is a mythic Creature — Demon card from Battlebond (BBD), collector number 44. Current market price: $23.30 (foil $33.09), TCGplayer market prices via Scryfall.
Flying Your opponents can't gain life. At the beginning of each end step, each opponent loses life equal to the life that player lost this turn. (Damage causes loss of life.)