Restless Fortress is a rare Land card from Wilds of Eldraine Promos (PWOE), collector number 259p. Current market price: $0.88 (foil $0.81), TCGplayer market prices via Scryfall.
This land enters tapped. {T}: Add {W} or {B}. {2}{W}{B}: This land becomes a 1/4 white and black Nightmare creature until end of turn. It's still a land. Whenever this land attacks, defending player loses 2 life and you gain 2 life.