Temple of Mystery is a rare Land card from Core Set 2021 Promos (PM21), collector number 254p. Current market price: $0.26 (foil $0.47), TCGplayer market prices via Scryfall.
This land enters tapped. When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.) {T}: Add {G} or {U}.