Castle Garenbrig is a rare Land card from Throne of Eldraine (ELD), collector number 388. Current market price: $16.31 (foil $48.58), TCGplayer market prices via Scryfall.
This land enters tapped unless you control a Forest. {T}: Add {G}. {2}{G}{G}, {T}: Add six {G}. Spend this mana only to cast creature spells or activate abilities of creatures.