Hall of Tagsin is a rare Land card from The Brothers' War (BRO), collector number 371. Current market price: $0.41 (foil $0.67), TCGplayer market prices via Scryfall.
{T}: Add {C}. {1}, {T}: Add one mana of any color. {4}, {T}: Create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")