Valgavoth's Lair is a rare Enchantment Land card from Duskmourn: House of Horror Promos (PDSK), collector number 271p. Current market price: $0.91 (foil $1.01), TCGplayer market prices via Scryfall.
Hexproof This land enters tapped. As it enters, choose a color. {T}: Add one mana of the chosen color.