Aquabolt

You conjure a turbulent sphere of water and launch it at a target. On a hit the target takes 1d6 cold damage and, if size Large or smaller, is knocked back 5 ft. Creatures made of fire are treated as having vulnerability to cold damage. 

This spell’s damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).