Finale of Devastation is a mythic Sorcery card from War of the Spark Promos (PWAR), collector number 160p. Current market price: $51.91 (foil $75.10), TCGplayer market prices via Scryfall.
Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.