Death-Rattle Oni is a uncommon Creature — Demon Spirit card from March of the Machine: The Aftermath (MAT), collector number 13. Current market price: $0.16 (foil $0.21), TCGplayer market prices via Scryfall.
Flash This spell costs {2} less to cast for each creature that died this turn. When this creature enters, destroy all other creatures that were dealt damage this turn.