Binding Choker (5e Equipment)
From D&D Wiki
Wondrous item, rare (requires attunement)
This choker resembles a collar made black iron and etched into the metal are scenes depicting death, suffering, and torture. Such collars can be found in the possession of cultists, greater undead and evil spellcasters. A collar will be associated with some powerful demon in the abyss. The exact number of these made are unknown.
When a creature comes into contact with the collar by touch, they instantly become attuned to it. Then, during the next long rest, the target must make a DC 16 Wisdom saving throw or wake up the next morning, with the collar suddenly being worn on their neck.
Donned by the Damned. When the collar is worn, it tightens and can't be removed, seemingly fusing itself with your skin. The only way to remove it is through a remove curse spell or other such spells.
Over the course of 6 days after the collar is first worn, the target wearing the choker begins to have strange dreams of torture, suffering, and the demon associated with the collar. Once these dreams begin, black lines will begin to extend from the collar and begin to cover the body. Once per day at dawn the target must make a DC 16 Constitution saving throw. On a failed save, the target has a 1d4 penalty to all ability checks, attack rolls, and saving throws they make for the next 24 hours. On a successful save, nothing happens. For each day they succeed the throw, the DC increases by 1. Failing the save resets the DC to 16. A greater restoration spell can also reset the DC, while a resurrection spell can rid the target of all of the symptoms, causing the collar to release itself from the target.
Bound For Eternity. If the collar remains on through the course of the 6 days, the targets body will be completely covered in black, inky darkness where they will fall into a trance-like state. While in this trance, they are incapacitated, and will be able to meet face to face with the being associated with the collar. The target will then be forced into eternal servitude by the demon, unable to reject their commands. Some demons keep these people as pets, servants, or beings for them to torture or all eternity. While their consciousness is bound in the abyss, the target's body will act as according to the demonic master. The body will manifest demonic marks on their bodies as their forms and minds become more and more twisted. Their creature type becomes fiend. The collar then vanishes, inextricably turning up elsewhere for another victim to find. The only way for others to determine the location of the collar is through as wish spell or any other means determined by your DM.