Bark Storm

You summon a whirlwind of sharp bark that swirls around you in a 15-foot Emanation for the duration of the spell. Any creature that starts its turn within 15 feet of you must make a constitution saving throw, taking 1d8 shlashing damage on a failure. On a successful save, the creature takes half as much damage. A creature makes this save only once per turn.

Using a Higher-Level Spell Slot. The damage increases by 1d8 for each spell slot level above 1.