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The Khala ("Path of Ascension") is the main religion of the protoss. It is based on a psionic philosophy that maintains a communal psionic link between all adherents. Followers are known as Khalai. Followers are further subdivided into at least five level of adepts.
The Original LinkEdit
In their quest to create the perfect lifeform the xel'naga returned to Aiur, one of their engineered worlds, and discovered the protoss. The protoss possessed many favorable traits but most distinct of all was their psionic link, a form of instinctive telepathy that enabled them to communicate with one another and work together efficiently even in large groups. The xel'naga saw the protoss as suitable for further elevation.
After a millennium of subtle manipulation the xel'naga revealed themselves to the protoss and interacted with the nascent species directly. However, the xel'naga discovered the maturation of the tribal social structure and the rise of individualism was adversely affecting the psionic link. Eventually the psionic link was broken. The protoss could still telepathically communicate and read each others thoughts, but the empathic bond was lost.
The Aeon of StrifeEdit
Near the end of the Strife a protoss named Savassan, later known as Khas ("he who brings order"), found the khaydarin crystals left behind by the xel'naga on Aiur. Savassan touched the crystals and rediscovered the psionic link. With knowledge gained from researching other xel'naga relics, Savassan learned how to rekindle the empathic bond. He recorded these findings, the founding precepts of the Khala, so that the protoss might once more become a unified communal society.
Many protoss both revered and hated the xel'naga and the hatred fueled the Strife. Khas believed the Khala would allow the protoss to embrace the positive emotions all protoss shared to negate the destructive self-hatred. As Khas saw it the protoss did not need the xel'naga, only the once-lost emotional link. Khas thus ended the Aeon of Strife and brought on the protoss' Second Age.
The Modern KhalaEdit
Based on the Khala, protoss society restructured to compose of three Castes: the Judicator Caste (led by the Conclave), the Khalai Caste and the Templar. When the protoss became an active interstellar civilization once more after the Strife, the Khala led them to adopt the Dae'Uhl ("Great Stewardship") over less advanced species they discovered.
Being subsumed in the Khala meant a certain loss of self in addition to the gain of the "other". There was a risk the loss could be drastic. As a result some protoss rejected the Khala and severed their long head nerve cords to cut the empathic link. These outcasts formed into the Rogue Tribes and were later known as the Dark Templar after their banishment from Aiur.
It is impossible for Khalai to hide from one another due to the empathic link. Hiding was possible for all protoss during the Aeon of Strife when the link was suppressed. Non-adherents, like the Dark Templar may still conceal themselves from other protoss.
The depth of the link varies according to personal choice. Generally it is difficult to be fully immersed in a state of unity all the time. Members of the Templar and Judicator Castes immerse themselves deeply several times per day, along with many Khalai, "nourishing" themselves through the rich contact and emerging refreshed and invigorated.
The Khala grants a protoss an enormous amount of psionic energy.
Khalai "enter" the Khala upon death but do not remain as complete or coherent entities. Their last thoughts are automatically gained by protoss in close proximity to the deceased. As a result Khalai may access memories and strands of experience of dead Khalai through the Khala, sometimes with the aid of the templar archives. However, only preservers have full access to this knowledge.
Communication within the KhalaEdit
Protoss can communicate using a mental link (which transmits emotions) or simply through "speaking" (another form of mental link).
Protoss can create a special kind of mind-meld deep within the Khala, where no one could lie. Protoss performing this kind of mind-meld hold up their hands and face their palms to each other; both palms softly glow. This kind of communication was also possible between Adun and Raszagal, the latter not following the Khala.
Combining with the VoidEdit
Utilizing the Void and Khala simultaneously grants protoss incredible power, but can result in the protoss burning out like a star. Protoss who can utilize both sets of power simultaneously are exceedingly rare. Known practitioners were Adun and Tassadar.