Chainer's Torment is a uncommon Enchantment — Saga card from Dominaria (DOM), collector number 82. Current market price: $0.22 (foil $0.30), TCGplayer market prices via Scryfall.
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I, II — This Saga deals 2 damage to each opponent and you gain 2 life. III — Create an X/X black Nightmare Horror creature token, where X is half your life total, rounded up. It deals X damage to you.