Wave of Thorns

Rath summons forth a 30-foot-long cone of thorny vines out from you in a direction you choose. Each creature in the area makes a Dexterity saving throw, taking 8d6 Piercing damage on a failed save or half as much damage on a successful one.

Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 3.