Mage-Ring Responder (ORI) from Magic Origins, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Adam Paquette
• Card Text:
  Mage-Ring Responder doesn't untap during your untap step.
  7: Untap Mage-Ring Responder.
  Whenever Mage-Ring Responder attacks, it deals 7 damage to target creature defending player controls.