Githzerai Zerth

(from Mordenkainen's Tome of Foes - 2018):

Zerthimon's mortal form died in battle, but his sacrifice freed the githzerai from Gith's dark designs. They believe that Zerthimon, in his new godly form, will return someday and usher them into new age of freedom. Until that happens, the githzerai known as zerths fill the symbolic role of Zerthimon in society, as accomplished wielders of psionic power who can move themselves and others between planes. 

The githzerai believe that when Zerthimon returns, he will first gather all the zerths and take them to their new paradise to prepare it for those who follow. Zerths are similar to what other races would call priests, although githzerai don't have a religion as such, beyond their admiration for Zerthimon and Menyar-Ag.

(from www.torment.fandom.com and the videogame Planescape: Torment - 1998):

Karach Blade:

"This blade appears to have special religious significance for Dak'kon. [He] has wound a series of parchments around the hilt of the blade [that] appear to be mantras dedicated to Zerthimon."

The weapon is a karach blade. "Karach" roughly translates to "chaos matter." It is a special substance that is shaped by its user's will.

This type of blade is significant to the githerzai people. Those who know the words of Zerthimon are zerth. They are fit to carry the blades, though it is only trusted to those who are most capable and possess immense self-discipline.

"It is a *karach* blade. It is an object that lets others *know* the rank of the wielder... The blade is a symbol carried by the *zerth.* A *zerth* is one who *knows* the words of Zerthimon. In *knowing* the words of Zerthimon, they *know* themselves."

- Dak'kon

(from 2nd edition Monstrous Manual):

Zerths are special among the githzerai, acting as focal points for the attention of Zerthimon. The githzerai believe that when Zerthimon returns for them, he will first gather all of the zerths and lead them to their new paradise. It might be said that the zerths are the center of githzerai religion. Unfortunately, they are not free from religious persecution.

(from 5th Edition Monster Manual - 2014):

Focused philosophers and austere ascetics, the githzerai pursue lives of rigid order. Lean and muscular, they wear unadorned clothing free of ornamentation, keeping their own counsel and trusting few creatures outside of their own kind. Having turned their backs on their warlike githyanki kin, the githzerai maintain a strict monastic lifestyle, dwelling on islands of order in the vast sea of chaos that is the plane of Limbo.

Psionic Adepts. The progenitors of the githzerai adapted to — and were transformed by — the psychic environment imposed on them by their illithid overlords. Under the teachings of Zerthimon, who called on his people to abandon the warlike ambitions of Gith, the githzerai focused their mental energy on creating physical and psychic barriers to protect them from attack, psychic or otherwise. Fighting is personal to a githzerai, which uses its mind to daze and incapacitate opponents, leaving them vulnerable to physical punishment.

Order amid Chaos. The githzerai willingly dwell in the heart of utter chaos in Limbo — a twisting, mercurial plane prone to manipulation and subjugation by githzerai minds strong enough to master it. Limbo is a maelstrom of primal matter and energy, its terrain a storm of rock and earth swept up in torrents of murky liquid, buffeted by strong winds, blasted by fire, and chilled by crushing walls of ice.

The forces of Limbo react to sentience, however. Using the power of their minds, the githzerai tame the plane’s chaotic elements, causing them to settle into fixed and survivable forms and creating oases and sanctuaries within the maelstrom.

Githzerai fortress-monasteries stand resolute against the chaos that surrounds them, virtually impervious to the turmoil of their surroundings, because the githzerai will it. Each monastery is overseen by monks that impose a strict schedule of chants, meals, martial arts training, and devotions according to their own philosophy. Behind their psionically fortified walls, the githzerai embrace thought, learning, psionic power, order, and discipline above all other things.

The social hierarchy of the githzerai is based on merit, and those githzerai who are the wisest teachers and the most skilled at physical and mental combat become leaders. The githzerai revere great heroes and teachers of the past, emulating those figures’ virtues in their everyday lives.

Disciples of Zerthimon. Githzerai revere Zerthimon, the founder of their race. Although Gith won their people’s freedom, Zerthimon saw her as unfit to lead. He believed that her warmongering would soon make her a tyrant no better than the mind flayers.

Skilled githzerai monks that best exemplify the teachings and principles of Zerthimon are called zerths. These powerful and disciplined monks can shift their bodies from one plane to another using only the power of their minds.

Beyond Limbo. Though githzerai rarely deal with the realms beyond Limbo, advanced monks of other races sometimes seek out a githzerai monastery and attempt to gain admittance as students. More rarely, a githzerai master establishes a hidden monastery on the Material Plane to train young githzerai or to spread the philosophy and teachings of Zerthimon.

As disciplined as they are, the githzerai have never forgotten their long imprisonment by the mind flayers. As a special devotion, they organize a rrakkma — an illithid hunting party — to other planes, not returning to their monasteries until they slay at least as many illithids as there are hunters in the party.