Nebuchian Cult

The Nebuchian Cult is an organization that arose among the religions civil war between Humenia and the Kingdom of Nozu, although it has had followers for an unknown amount of time. It rose to prominence during the religious conflicts and, through an unknown method, managed to secure the area known as Laureyria to the southeast of Humenia. There, they established a theocracy not unlike the designs of Nozu and Humenia themselves, but instead are fixtured around the Nebuchian Mythos and the worship of their god.

Nebuchian Lore

Nebuche was Galde's brother who loyally served and followed Galde through the tribulations that ultimately led to his ascension to godhood. While Galde alone took the throne, Nebuche was left to the mortal word as a messenger for Galde. However, Nebuche learned something from Galde's tribulations that differed from the headstrong and ambitious Galde himself. Nebuche found that the essences of mortality (Death, Sickness, Filth, Change, and Desire) were as inevitable as the gods themselves. Nebuche, having watched a mortal ascend, did not believe that gods were the final end of power and righteousness. He grew to believe that mortals were (or at least, could be) equal to the gods and shaped the world in parallel to them. He believed that while mortality meant you could die, it also meant you could multiply. 
Nebuche moved to master a Method of Magic, derivative of the divine and called it Transformation. While most magics of the time were derived from the power of gods, Nebuche wanted to utilize the inherent power of mortals and succeeded. This, however, was much weaker on an individual basis and required materials on the mortal plane for this to work. Nebuche set out to strengthen this magic somehow, first through sheer numbers and second through natural means. The first seemed to be a failure, as people could only draw on their own magic and could not combine their magics in the same way that rituals were performed using Divine magic. The second was successful, and Nebuche found that using the inherent magic of non-sentient life one could manipulate them in useful ways. Thus, Nebuche created the First Method of Magic, Primal. While powerful, this was not the Transformation Method he sought.
Nebuche re-examined his first effort. He instead looked to use the essences of mortality as a source of magic. These experiments were a success, but quickly drew the ire of the gods themselves. Nebuche used blood, life, and filth to create his magics, and to many this was directly heretical to the gods. Nebuche was able to use these essences to transform the world itself, its people, and enhance mortality to a form previously unfamiliar to the world. If the gods sent a boon, Nebuche would change it. If the gods sent a curse, Nebuche would change it. Thus, Nebuche created the Second Method of Magic, Transformation. 
When the gods sought to end Nebuche, he instead escaped to a place where the gods could not reach him. He did not abandon his mortality as his brother did. Instead, Nebuche changed and can be found in those who seek Transformation. He dies, he is born, he is filth, he is clean, he is mortal. 

Nebuchian Practice

Cultists believe that Arcane magic is the Fourth Method of Magic, accidentally made when the Exodus occurred as echoes of the Third Method of Magic: the Divine. Both Methods are considered heretical, along with some practices associated with them that are not inherently magical. They do not think that nobody should use Arcane magic, but instead believe that among their followers they should be solely focused on Transformation. Primal magic is held in high esteem as an invention of Nebuche himself, but not considered a path to Nebuche's goal.
The underlying belief of Cultists is that mortality can supplant the need of gods and hold their own power equivalent to them. Transformation is the mortal equivalent of the divine, and so each Cultist is taught its use and encouraged to experiment with it. Most of the world calls this magic Transfiguration or Transmutation, but the cultists consider these forms of Transformation are weaker than their own. 

Nebuchian Worship

While most of their organizational structure is not unlike the Nozuan theocracy, albeit with one focus rather than many, the typical Nebuchian cultist differs in the following ways:

Writing is considered a boon of the old gods around the world, and therefore not of mortality like speech and symbols. Cultists can only learn to read that which was created by mortals and has lead to a specific script unknown to the rest of the world. It is written like a cypher of heiroglyphs and was created to avoid most written patterns. It is difficult to learn how to write correctly, but relatively easy to understand with simple education. Cultists typically use symbiology to communicate in any way that it is deemed necessary to do so, and few are taught this script in the first place. The idea is that if you need to send a message, you can draw it.

The method of sacrifice is centered entirely on the essences of mortality. This means death is considered a tool, as well as blood, filth, and anything else that is essential to being mortal. Cultists utilize all these things in their rituals and it is considered holy to constantly offer as much of your mortality to Nebuche as possible. To the outside eye, this creates a population of exceptionally clean and disease free people as an act of worship is ridding yourselves of these essences.

Rituals of the priests of Nebuche involve Transformation magics. They have been doing this for years, and have developed really obscure applications of Transformation using the offerings of the cultists. This has included a method of transportation of materials and, presumably, people that was discovered when Priests tried to find where Nebuche escaped to from the gods. The exact method of this magic is unknown and closely guarded, but it can be assumed that the sacrifices of filth, waste, and life are necessary components.