Channeled Dragonfire is a uncommon Sorcery card from Tarkir: Dragonstorm (TDM), collector number 102. Current market price: $0.22 (foil $0.27), TCGplayer market prices via Scryfall.
Channeled Dragonfire deals 2 damage to any target. Harmonize {5}{R}{R} (You may cast this card from your graveyard for its harmonize cost. You may tap a creature you control to reduce that cost by {X}, where X is its power. Then exile this spell.)