Mage-Ring Responder is a rare Artifact Creature — Golem card from Magic Origins (ORI), collector number 232. Current market price: $0.20 (foil $0.48), TCGplayer market prices via Scryfall.
This creature doesn't untap during your untap step. {7}: Untap this creature. Whenever this creature attacks, it deals 7 damage to target creature defending player controls.