Erribin's Cinder Strike

You conjure a furiously burning line of flame in your hands that assumes the shape of an arrow. The flames can fly up to 60ft away from you in a 5ft wide line, piercing through any target in the way. At the end of its trajectory, the arrow explodes, releasing a blast in a 10ft radius of its endpoint. Each creature struck must make a Dexterity saving throw. A creature takes 8d6 fire damage on a failed save, or half as much damage on a successful one.

The arrow ignites flammable objects in the area that aren't being worn or carried.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.