Nerve swimmer

Nerve swimmers were derived from immature illithid tadpoles and were used as living instruments of torture and interrogation.

Description
Nerve swimmers were minuscule, enough so that casual visual inspection revealed few details.

Personality
Nerve swimmers were undoubtedly malevolent: they enjoyed the cruel tasks that they had been created for and, when independent, undertook similar or worse tasks on their own.

Abilities
Nerve swimmers moved in swarms of at least dozens of individuals, and often such swarms kept company with each other. Like all swarming creatures, they could easily surround foes, while being difficult, if not impossible, to damage with conventional weapons; an enemy so surrounded by nerve swimmers risked being nauseated at the creeping, crawling bodies swarming over their own.

Moreover, like the mind flayers they were derived from, nerve swimmers had quite a few innate psionic talents: all nerve swimmers in a given swarm formed a hive mind, could telepathically communicate with any intelligent creature within of the swarm, and, while in possession of a host, could discern lies thrice each day.

Perhaps the most horrifying ability of a nerve swimmer swarm was that they could burrow into the flesh of a victim, as parasites in a host. While hidden in such a host, they lacked the physical traits of a swarm, but wielded several psionic talents: they could control the host's body directly for six minutes once per day, induce wracking pain in the host thrice each day, and, five times per day, could simply paralyze the host by shutting off their nerve impulses.

Ecology
Nerve swimmers had first been created as instruments of torture and interrogation, a task they succeeded at and enjoyed, easily controlling victims in the service of the swarm's master. Swarms without masters found their own goals and schemes, and enslaved creatures for the purposes of furthering those goals. Drow wizards were a favorite host amongst independent swarms: possessing the authority and reputation to get things done, but lacking the physical prowess needed to endure the torture of nerve swimmers.

Nerve swimmers were long-lived and, if they went too long without a host, would have to hibernate for long periods of time. During hibernation, some members of the swarm would die, spreading their vital energy to the other members, who then made new nerve swimmers.

In the illithid city of Oryndoll, members of the Abysmal Creed were known to experiment with nerve swimmers to spread terror among other creatures. These experiments with illithid tadpoles were considered distasteful even by other illithids.