Aqua Blast

You fire a high-speed burst of glowing water from your outstretched palm in a Line that is 25 ft. long and 5 ft. wide. Each target in that area must make a Dexterity saving throw, taking 3d6 bludgeoning damage and be knocked back 10 ft. from their current location and knocked prone on a failed save, or half as much damage and no other effects on a success. 

Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 2.