Entropy

You focus the decaying essence of death onto a point within range.

Each creature within a 20 ft. radius centered on the point you choose must make a Constitution saving throw. On a failure, a creature takes 4d8 necrotic damage and its speed is halved for the duration. On a success, a creature takes half as much damage, and its speed is not reduced.

A target that fails its saving throw must make a Constitution saving throw at the end of its turn before taking 2d8 necrotic damage - on a success, the target takes no damage, and the spell ends for that creature.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the initial damage increases by 1d8 per level of spell slot above 4th.