Dromar's Cavern is a uncommon Land — Lair card from Planeshift (PLS), collector number 138. Current market price: $0.57 (foil $26.12), TCGplayer market prices via Scryfall.
When this land enters, sacrifice it unless you return a non-Lair land you control to its owner's hand. {T}: Add {W}, {U}, or {B}.