Tempests Fury

A storm cloud the size of the casters choosing appears above the target and releases two lightning bolts that can strike two different targets or a single target twice, the creature must make a Dexterity saving throw. A creature takes 3d8 lightning damage on a failed save, or half as much damage on a successful one.

The lightning causes partial paralysis on any target that fails its save causing it to have a disadvantage on attacks and half movement speed for 1 round 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d8 for each slot level above 2rd.