Atrophic Pulse

A sphere of necrotic force sweeps out from you. Each creature in a 15-foot sphere originating from you must make a Constitution saving throw. On a failed save, a creature takes 1d8 necrotic damage and 1d8 force damage and has its speed halved until the end of your next turn. During this time, the necrotic energy causes a targets muscles to temporarily atrophy. On a successful save, the creature takes half as much damage and doesn't have its movement halved.

At Higher Levels: When you cast this spell using a spell slot of 2nd Level or higher, the damage increases by 1d8 for each slot level above 1st, alternating between 1d8 necrotic and 1d8 force.