Bind to Nyx

A spell granted by the staff called Ainigma

A pool of Nyx appears beneath a creature spilling out in a 10-foot radius. Four starry arms reach out from the pool and grasp the target, attempting to pull them under. For the duration, this pool turns the ground in the area into difficult terrain.

The creature targeted by this spell must succeed on a Wisdom saving throw or be restrained by the arms until the spell ends. A creature grasped by the pool can use its action to make a Wisdom check against your spell save DC. On a success, it frees itself. On three fails, the creature is submerged into the pool and is bound to Nyx for as long as Kruphix sees fit.
When the spell ends or the creature is submerged, the Nyx pool vanishes.