Dawn of the Gods
Like so many other illithid cities, Oryndoll depended on its enormous slave population for its continued prosperity. The elders of Oryndoll had a unique method to prevent their slaves from escaping: a great psychic barrier surrounding the city. But thanks to a mysterious stranger, the slaves of that terrible underground city developed a plan to pierce the barrier and make their escape. The plan relied on provoking one of the cruelest punishment that the mind flayers could inflict: the dergolt.
Causing no physical harm, the dergolt was a bolt of psychic energy that inflicted mental anguish that would linger for some time, fading away slowly. The slaves’ escape plan relied upon receiving the dergolt so that the psychic energy could be infused into links of a chain secreted upon the victim’s body. These links, when combined, would have sufficient power to temporarily overload the barrier, providing an opportunity to escape.
After a year of psychic torment suffered by the would-be escapees, the enchantment of the links was complete. Most of the psychic energy was drained off in the successful escape attempt, but the chain retained significant power after piercing the barrier. The dwarven smiths who had created the links using a secret process called residuum cold-forging used the chain to craft a kusari-gama for the slave who had led the escape.