Water Pulse

A 5ft jet of water erupts from your hand in a direction you chose in a 75ft line. Any creature in its path must make a dexterity saving throw or be knocked prone and take 8d6 force damage. On a successful save the creature remains standing a nd takes half. If the creature is susceptible to water based damage they take an extra 3d6 regardless of save. 

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