Echoing Deeps is a rare Land — Cave card from Edge of Eternities: Stellar Sights (EOS), collector number 103. Current market price: — (foil $19.90), TCGplayer market prices via Scryfall.
You may have this land enter tapped as a copy of any land card in a graveyard, except it's a Cave in addition to its other types. {T}: Add {C}.