Wall of Death

You create a wall of necrotic energy on a solid surface within range. You can make a wall up to 60ft long, 20ft high and 1ft thick, or can make a ringed wall up to 20 ft in diameter, 20ft high, and 1 ft thick. The wall is opaque and lasts for duration. When the wall appears, each creature within its area must make a CON saving throw. On a failed save, a creature takes 5d8 necrotic damage and the first time it drops to 0 hit points within the next minute, it instantly fails a death saving throw; on a successful save, it takes half as much damage without the other effect. You regain hit points equal to half the amount of necrotic damage dealt. One side of the wall, selected by you when you cast this spell, deals 5d8 necrotic damage to each creature that ends its turn within 10 ft 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.