Thunder Cats

You form a large cat out of lightning that runs you enemy's down. The target must make a constitution saving throw. On a failed save the target takes 2D6 Lightning damage and is stunned until the end of your next turn. If the target makes the save they take half damage and are not stunned.

When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each slot level above 1st.