Bellowing Bard - Rystix' Breath of the Gales

You gain resistance to Lightning damage. When you take the Attack action on your turn, you can replace one of your attacks with an exhalation of magical energy in either a 20-foot Cone. Each creature in that area must make a Strength saving throw (DC 8 plus your Spell Casting or Attack modifier and Proficiency Bonus). On a failed save, a creature takes 2d10 Bludgeoning damage. On a successful save, a creature takes half as much damage.

You can use this Breath Weapon once per Long Rest.