Combustion Technique is a uncommon Instant — Lesson card from Avatar: The Last Airbender (TLA), collector number 128. Current market price: $0.23 (foil $0.31), TCGplayer market prices via Scryfall.
Combustion Technique deals damage equal to 2 plus the number of Lesson cards in your graveyard to target creature. If that creature would die this turn, exile it instead.