Thelma's Acid Fang

A shadow of a Cobra comes out of your back and bends over your head shooting a line of acid 100 feet long and 5 feet wide in a direction you choose. Each creature in the line must make a Dexterity saving throw. A creature takes 5d6 acid damage on a failed save, or half as much damage on a successful one. At the end of its next turn it takes another 2d6 acid damage or half as much if it succeeded its Dex save. The acid will tear through walls that are made of wood or hay and continue for up to half of its remaining distance.

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