Deep Magic Volume 2 (p.215)
Reshape Skeleton
4-level Necromancy
Casting Time: 1 action
Range/Area: 60ft.
Components: Verbal, Somatic, Material
Materials: a pinch of powdered giant bone
Duration: Concentration, 1 minute
Attack/Save: CON Save
You cause one creature you can see to suffer a bonecracking rearrangement of its skeleton. Choose one creature you can see within range that has a bony or cartilaginous skeletal structure. That creature must make a Constitution saving throw or its bone structure becomes mutable for the duration.
Until the spell ends, you can use a bonus action on each of your subsequent turns to adjust the target’s bone structure, limiting its ability to act. The target must succeed on a Constitution saving throw or take 3d10 bludgeoning damage and suffer one of the following effects of your choice until the end of its next turn: halved speed or disadvantage on attack rolls.
At the end of each of its turns, the target can make another Constitution saving throw. On a success, the spell ends on the target.
At higher levels: When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d10 for every two slot levels above 4th.
Available for: Bard, Sorcerer, Warlock, Wizard