Guardians are conscripted Sentient beings that have had Essence modification through a combination of Quantumancy and Biomancy in the Whisper world to be granted limited augmented magical abilities while tethering their existence to a particular purpose. The primary purpose and function of a Guardian was to be able to see and weave the "cycles" of the Whisper world from outside of Radiance, but the modification of their Essence would bind them to do no harm to the state of Whisper or the cycles.
The Bakian Guardians of Stairell
The Stairellans conscripted numerous Bakians in order to create Guardians that would be the caretakers and curators of Brilliance, obeying orders to "reset" and rebuild Brilliance while removing "corruption" from the realm. In modifying these Bakians' Essence, the Stairellans were able to ensure the conscripted Bakians had no way to harm them and no way to avoid following instructions. To protect their creations, a safeguard was implemented that would cause the Bakians to mutate into mindless, atrocious canine-like monsters of shadow and blood, invulnerable as they would leave death and devastation in their wake. This form is ephemeral but sustained long enough for the Guardian to destroy everything in its wake before dissipating into nothingness.
Normally, a large number of Guardians were required to work in concert in order to exact efforts as instructed by the Stairellans upon Brilliance; however, special cases such as The First Guardian and Guardian Primes were not subject to the same restrictions and fate as traditional Guardians. Unfortunately, these "reset" powers came at a great cost, often consuming the Bakians that conducted them. Over time, this contributed to the Guardians' desire to wage war against those loyal to Stairell over the exploitation of their people.
The Emissaries of Baku
Prior to the Guardian project in Stairell, attempts were made to select delegates from various tribes on Baku to represent the people. In reality, this was an effort of the Stairellans to meddle in the affairs of Bakians and create weapons of their own people which they could employ covertly and at-will to the various nations across Baku, while experimenting with risky magics the Stairellans were unable to control. After failed attempts to create Stable Elements of Annihilation (Death, Famine, Pestilence, and War) and with the advent of progress in the Guardian project, the Emissary project was abandoned and the four Bakians that were select (Azazel of the South Tribe, Shuya of the East Tribe, Hastur of the West Tribe, and Ubaku of the North Tribe) were returned to their people. Eventually it was discovered that the Emissary program succeeded, as each of the Emissaries became representations of the parts of Annihilation element; however, this consumed and malformed those Bakians Essences beyond a point of no return, creating an unstoppable Sentient force with no purpose or desire other than to curate and see to the end days.
The First Guardian
After observing conflicts on Baku, the Kingdom of Stairell took steps to ensure its isolation and sovereignty through a program to use the natural outside life Radiance created on Baku to protect the eldest core lives of the Stairellans. During the Emissary program, the Stairellans had mastered biomancy and quantumancy on Sentients in a way that would properly and safely augment the capabilities of the individual. While the process did not appear to take well on the Svanian race, Bakians were very susceptible to process, and thus Bakians were chosen to be the subjects of the Guardian program. The First Guardian was the success that was used as a template for improvement and correction to all Guardians that came after.
The Guardian Primes
The first set of stable Guardians to come after The First Guardian were called Guardian Primes. The consist solely of Bakians. Once the Guardian program was a success, the first Guardians to be created were forged in the likeliness of each of the Stable Elements and their Council, as this allowed safer progress in developing a more universal process that could be applied to any Bakian with little oversight and maintenance. Among these Guardian Primes were Sabaku, Raos, Visvasa, ???, ???, ???, ???, and ???.
Similar to the quantity needed to power a Celestial Nexus, several Guardians could unite their gift and call forth a "reset" of the Brilliance crystal from the outside of it. While this would not change much within Brilliance itself other than removing a small instance of "corruption" from their world as if it never transpired, it could take an unknown amount of time to complete for those outside. With the volatile shifting lands of Baku, this meant many Guardians permanently lost the ability to return home sometimes after performing a reset.
It should be noted that not all Guardians were created equal. Often times the abilities granted to Guardians were toned down from the ability the first Guardian received in testing. Some Guardians, like the first Guardian, were imbued with a greater ability to manage creating and de-creating than others depending on the depth of their involvement and loyalty. For example, the first Guardian could recreate life from a template if necessary to restore corruption-less life without removing the life or creating a divergent path for that life. Ultimately, anything that had the ability to directly diverge the history or future paths of Stairell was locked behind the "Will of Stairell" to prevent foul play.
The Blood Oath
Sometime after the creation of the first Guardian, Xii created a blood-based magical alteration for life created from Radiance. While its effects did not apply to the first Guardian due to a state of corruption from so many alterations, all other Guardians, including the Emissary program Guardians, were bound by its effects. Ultimately, they are instinctively bound to pursue the "Will of Stairell" with senses detecting when the state of the realm is at risk. Additionally, they were granted means to supercede death for a limited time. When a Guardian expires, the blood-magic consumed their entire being, creating a monstrous, uncontrollable canine entity that appears to be made of the black skies itself. This creature is immortal until the entire soul and Essence of the Guardian is consumed, terminally ceasing their existence. Few accounts exist of encounters of these "activated" Guardians, and rumors suggest they're powerful enough to tear through reality itself with their claws and eerie fangs. The only way to defeat a Guardian in this form is to survive until the Essence is fully spent.
Guardians, other than the four from the Emissary group, were given Vedatech including masks and weaponry. Masks varied in their ability depending on the type and some could connect to Prana Vikaria to obtain and disburse information for Guardians. The masks would create a guarded network among themselves solely for Prana Vikaria data. Mask types included functions for navigational with the ability to control vessels like a Celestial Nexus remotely. Masks for combat use stored combat data of an individual and replicated it, even if the body was unconscious, continuing to fight or flee in place of the conscious Guardian. Some masks contained hyperlogic functions, able to rapidly analyze strategy or solve problems before they'd occur.
Guardian weaponry were high-tech items that generally carried an elemental affinity. For example, one Guardian was known to carry a greatsword and clawed hand-to-hand weapons. These were imbued with a single red gemstone that would turn purple when activated, controlling lightning. The Guardian would have the ability to call and control lightning from virtually any source around him, even amplifying it by storing it within the weapon for a time.