The Y?g? protocol, for lack of a better word, is an application of advanced Imbrian Dimensional Science and psychtronics that summons a celestial fragment and invests it into an organic host. This was a culmination in Imbrian Imbuement, turning mundane creatures and humans into beings far beyond their biological potential.
The first forays into the creation of the Y?g? protocol yielded youma and feral monsters that couldn't be controlled. The power of the entities created in these first attempts was impressive, but their uncontrollable nature made them less than useful. These creatures were used as subjects of Wild Hunts, where the heroes of the Dynasty would ride after the beasts and slay them in combat.
The Last Queen
The study of Y?g? was a central fascination of Be'al Sio, the last dynastic queen of Imbria. Her studies of the spheres of creation, both those of past shed realities, and realities yet to be born, allowed her to divine the nature of the celestial fragments, to understand what they were, and their place in the universe. This great and terrible knowledge drove Sio beyond the cusp of madness. She left the Royal See and the Crystalline Palace to dwell in a nameless valley in the lunumbra (the dark side of Luna) where her madness overtook her. For a great time she reveled in insanity, and learned secrets that no mortal was meant to know.
After Sio returned from the lunumbra, she was changed. Her smile has hard, and her eyes glinted like cold stone. She bore with her a strange device, a black sphere of unknown material, either an artifice of her own hands or something that she discovered in her research. The black sphere shown with a crimson light, and those who saw it knew that it was unwholesome. This was the central device of the Y?g?, and in truth it was the Heart of Bekoriel.
The Heart of Bekoriel was a dirac solenoid, the arcane organ/engine that is found in the heart of a type of Outer God known as an Erelim. Similar to teratomorphs, Erelim are dramatically much more powerful and demonstrate the ability to levitate and fly, can exist in the void of space, can generate energy beam attacks, and project defensive barriers to protect themselves from harm. Bekoriel was found dormant, almost completely buried under the regolith of Pluto. The Queen had made the long voyage to the distant world and with her powers cut it out of the torpid form of the dead godling.
Sio took the Black Sphere and made it into a scepter, creating a very powerful arcane device, one that would serve as a symbol of her rule, and an implement of her plans. Her scepter had three important powers that she used on a regular basis.
Parapsychic Battery/Conduit - the Black Sphere could hold and assist in channeling enormous amounts of cosmic power, allowing Queen Sio to perform unimaginable feats, including interplanetary teleportation, levitation of objects in the 100+ kiloton range, and controlling the emotions of everyone within a planetary radius.
Youma creation - with the scepter, the Queen could turn anyone or anything into a cosmic horror infested youma, under her complete control. This was done for a variety of reasons, but her entertainment was the most common. Sio enjoyed cursing women she found threateningly pretty, or those who even remotely displeased her. When they wore out their usefulness, they would be executed, typically fed to something nasty.
Summoning Magnagogs - also known as teratomorphs, the Black Sphere could be used to summon titano-fauna to serve the Queen. These titans were typically used as her champions in dynastic disputes
The Black Sphere was unknown to the Imbrians, but Bekoriel was not. The Erelim had ventured into the inner solar system a number of times, but each time it had been driven back by the Imbrian knights, and the early kings and queens. These were the warriors and leaders who would eventually the Imbrian Dynasties. The last time Bekoriel meandered into the inner solar system, it was met by a host of magnagogs, most of which were wild, and there was a terrible fight. Bekoriel slew the magnagogs but was weakened enough that the Imbrians were able to drive the erelim into torpor. Believing the creature dead, they took the corpse to the distant cold world of Pluto, and dug it a tomb there and buried it. Deeply wounded, but slowly regenerating, Bekoriel would have eventually risen again, but the frozen burial slowed the process. When Sio arrived at the Mausoleum of Bekoriel, its wounds were barely recovered from that battle. With a blade, an ancient weapon forged from one of the erelim's own claws, she cut it open until she found it's heart, the black sphere, and removed it.
The entity Bekoriel had been a scourge of the Earth, returning to the planet every few million years to decimate the ecosystem and feed on it. it was largely responsible for the periodic extinction events that wracked the planet every 30 some odd million years. The Imbrians were the first culture advanced enough to drive it into torpor.
Yogo was the sacred rite that fuses a corporeal body with a non-corporeal entity, a willing and harmonious fusion of beings to create a new, unique, and powerful being. The Youma were but stepping stones, as they fused weak to weak, to make something of moderate strength.