Koth of the Hammer is a mythic Legendary Planeswalker — Koth card from Secret Lair Drop (SLD), collector number 1248. Current market price: $5.40 (foil $5.16), TCGplayer market prices via Scryfall.
+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.'"