Narset's Rebuke is a common Instant card from Tarkir: Dragonstorm (TDM), collector number 114. Current market price: $0.12 (foil $0.14), TCGplayer market prices via Scryfall.
Narset's Rebuke deals 5 damage to target creature. Add {U}{R}{W}. If that creature would die this turn, exile it instead.