Arrow of Necrosis

A arrow of black, necrotic energy forming a line 100 feet long and 5 feet wide blasts out from you in a direction you choose. Each creature in the line must make a Dexterity saving throw. A creature takes 8d6 necrotic damage on a failed save, or half as much damage on a successful one.

The arrow withers any non magical plants in its path instantly. 

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.