Undercity Sewers is a rare Land — Island Swamp card from Murders at Karlov Manor Promos (PMKM), collector number 270p. Current market price: $24.45 (foil $28.64), TCGplayer market prices via Scryfall.
({T}: Add {U} or {B}.) This land enters tapped. When this land enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)