Whips of Hadar

You touch one willing creature and invoke the power of Hadar, the Dark Hunger. Choose acid, cold, necrotic, or psychic. Tendrils of the chosen energy grow from the creature. Until the spell ends, the creature can use an action to perform a whip attack of the chosen type in a 15-foot cone. Each creature in that area must make a Dexterity saving throw, taking 3d6 damage of the chosen type on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d6 for each slot level above 2nd.