Wall of Lightning

You create a wall of lightning within range. You can make the wall up to 60 feet long, 20 feet high, and 1 foot thick, or a ringed wall up to 20 feet in diameter, 20 feet high, and 1 foot thick. The wall is opaque and lasts for the duration.

If the ends of the wall are not anchored to a power source, the duration of this spell is instead 1 round. If a ringed wall is created, only one power source is required.

When the wall appears, each creature within its area must make a Dexterity saving throw. On a failed save, a creature takes 5d8 lightning damage, or half as much damage on a successful save.

One side of the wall, selected by you when you cast this spell, deals 5d8 lightning damage to each creature that ends its turn within 10 feet of that side or inside the wall. A creature takes the same damage when it enters the wall for the first time on a turn or ends its turn there. The other side of the wall deals no damage. 

If a power source that the wall is anchored to is destroyed or is turned off, the spell ends after one round.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d8 for each slot level above 4th.  Furthermore, if a creature takes more than 50 damage from this spell within 5 consecutive rounds, the creature must make a Constitution saving throw. On a failed save, it is stunned for one round.