Mirrorpool is a mythic Land card from Oath of the Gatewatch Promos (POGW), collector number 174s. Current market price: — (foil $16.18), TCGplayer market prices via Scryfall.
This land enters tapped. {T}: Add {C}. {2}{C}, {T}, Sacrifice this land: Copy target instant or sorcery spell you control. You may choose new targets for the copy. {4}{C}, {T}, Sacrifice this land: Create a token that's a copy of target creature you control.