Select a humanoid with limbs. They must make a constitution saving throw. On fail, your choice of limb desiccates and withers into uselessness. If the limb held something, it no longer can, nor be used for somatic components of spells. If the limb was vital to a movement of the target, they lose that movement. If the limb kept the target upright, they fall prone, and cannot stand. The effect of wither limb is undone if the target recovers HP equal to the caster's Wizard level or greater.