Darkflame Arrow

The arrow deals normal damage and wreaths the target in black flame that deals an extra 2d6 points of damage. The black flames continue to engulf the victim for 2 more rounds, dealing 2d6 points of damage each subsequent round (at the start of your turn), and they cannot be
extinguished (although they can be dispelled). The arrow or bolt must be fired during the same round the spell is cast, or the magic dissipates and is lost. Creatures with immunity or resistance to fire take full damage from the black flames.

At Higher Levels: When you cast this spell using a 3rd level or higher spell slot, you deal an additional 2d6 fire damage and the target is wreathed in flames for one more turn per level.