Aided by a certain ritual, the Vahnatai have the ability - after death - to let their spirit coalesce and bring it into physical form. The soul takes the shape of a deep blue crystal that is between two and three feet long and weighs around 300 stones. Only the wisest and most powerful of the Vahnatai leaders receive this honor. Vahnatai who turn themselves into crystal souls without being granted permission - and those living Vahnatai that aid them - are ostracized from society and forced to live in exile.
Vahnatai who will become crystal souls after death also bear this title, but since this honor is usually granted only shortly before death, the title Bok is very rarely borne by living Vahnatai.
In their new form, crystal souls enjoy vastly enhanced mental and spiritual faculties. They have a near perfect memory and supreme powers of concentration and reasoning. Their magical powers - great for a Vahnatai - become immense. However, they are not immune to mental harm - in some ways, they are even more sensitive than corporeal Vahnatai.
Either through a mistake made during the ritual, or through cruelties inflicted upon the soul, the soul may fracture and become unstable or even insane. The most dangerous of these necessarily are exiled - there was one such soul in the Black Waters between Vahnatai lands and Exile. Other fractured souls may continue to live among the Vahnatai, as Vyvnas-Bok did.
Crystal souls can communicate with Vahnatai and humans by projecting their thoughts into their minds. Communicating with humans is painful for both parties, so it is rare that a crystal soul will choose to speak with a human unless they have information of great importance.
Crystal souls are the Vahnatai's most important and influential advisors. They spend their days focusing on the further pursuit of knowledge and contemplating the current problems facing their people. As such, they are revered by all Vahnatai, and harming a crystal soul is unthinkable. Even when Gaddika betrayed three crystal souls to the Empire, he did not harm them and tried to make the Empire agree as well.