Kaleidoscorch 133 (Modern Horizons 2)

Converge — Kaleidoscorch deals X damage to any target, where X is the number of colors of mana spent to cast this spell. Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

NM - $0.70
LP - $0.70
MP - $0.70
HP - $0.70
DMG - $0.70