Castle Embereth is a rare Land card from Throne of Eldraine (ELD), collector number 239. Current market price: $0.38 (foil $0.93), TCGplayer market prices via Scryfall.
This land enters tapped unless you control a Mountain. {T}: Add {R}. {1}{R}{R}, {T}: Creatures you control get +1/+0 until end of turn.