Is Koth of the Hammer legal in Standard, Modern, and Commander?

Koth of the Hammer is legal in: Modern, Legacy, Vintage, Commander.

Koth of the Hammer

Q: What type of card is Koth of the Hammer?

Koth of the Hammer is a Legendary Planeswalker — Koth. Its oracle text reads: "+1: Untap target Mountain. It becomes a 4/4 red Elemental creature until end of turn. It's still a land. −2: Add {R} for each Mountain you control. −5: You get an emblem with "Mountains you control have '{T}: This land deals 1 damage to any target.'""