Water Blade

You conjure a razor-sharp blade of water and fling it forward. In order, each creature in that area must succeed on a Dexterity saving throw. The first creature in that line that failed its save, takes 5d12 slashing damage. The water blade continues flying forward, losing power whenever it hits a target. The following target in the line that failed its save takes only 4d12 damage, the next target only 3d12, and so on. When reducing the damage subtract the highest rolled die from the remaining result. The water blade dissolves once its damage reaches 0d12 or it reaches the end of the line. A creature reduced to 0 hit points this way, is killed and sliced in half.

Using a Higher-Level Spell Slot. The range increases by 10 feet and the damage by 1d12 for each spell slot level above 3.