Is Mage-Ring Responder legal in Standard, Modern, and Commander?

Mage-Ring Responder is legal in: Modern, Pioneer, Legacy, Vintage, Commander.

What type of card is Mage-Ring Responder?

Mage-Ring Responder is an Artifact Creature — Golem. Its oracle text reads: "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. Power/Toughness: 7/7"