Unfortunate Accident is a uncommon Instant card from Outlaws of Thunder Junction (OTJ), collector number 111. Current market price: $0.24 (foil $0.07), TCGplayer market prices via Scryfall.
Spree (Choose one or more additional costs.) + {2}{B} — Destroy target creature. + {1} — Create a 1/1 red Mercenary creature token with "{T}: Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."