Dimir Keyrune is a uncommon Artifact card from Gatecrash (GTC), collector number 228. Current market price: $0.26 (foil $1.26), TCGplayer market prices via Scryfall.
{T}: Add {U} or {B}. {U}{B}: This artifact becomes a 2/2 blue and black Horror artifact creature until end of turn and can't be blocked this turn.