Enialeigh's Explosive Arrow (Arteria)

You touch a quiver containing arrows or bolts. When a target is hit by a ranged weapon attack using a piece of ammunition drawn from the quiver, the target takes an extra 6d6 fire damage. In addition, each creature (excluding the initial target) within a 20ft radius of the target must make a Dexterity saving throw. On a failed save, targets take 3d6 fire damage or half as much on a successful save. The spell's magic ends on the piece of ammunition when it hits or missed, and the spell ends when eight pieces of ammunition have been drawn from the quiver.

Using a Higher-Level Spell Slot. The damage in both instances increases by 1d6 for each spell slot level above 5.