Dubhán's Step

Stomping forward with a wild step, abyssal magic thrusts you to an unoccupied space you can see within range, leaving a 5 feet wide line of fire between the two points. each creature within 5 feet of the line you left must make a Dexterity saving throw. On a failed save, a creature takes 1d8 fire damage, or half as much damage on a successful save.

The fire ignites any 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 2nd level or higher, the damage increases by 1d8 and the range increases by 10ft for each slot level above 1st.