Wall Of death

You create a wall of black smoke on a solid surface you can see within range. You can make the wall up to 60ft long 20ft high, and 1 foot thick, or up to 20ft in diameter 20ft high 1 foot thick.

When the wall appears each creature within it's area must make a CON saving throw. On a failed save take 4d8 necrotic damage, or half as much on success.

Both sides of the wall deal 4d8 necrotic damage to each creature that ends it's turn within 10ft of the wall. A creature takes the same damage when it enters the wall for the first time.

At higher levels: when this spell is casted at a spell slot 4th or higher, the damage increases by 1d8 per slot level above 3rd