The Immors was an aspect of the |Greater Cosmic Law| that governed life and death. Emmae was the first to comprehend it to exceedingly impressive levels eons ago. She devised ways for her followers to use glimmers of it in combat. The core of her forces, Liches, were explorers and conquerors, after all.
The Quasi Immors Soul Arts were the standard form of power required for one to become a Lich. As it happened, being able to use even one form judged a user's comprehension of the universal concept known as the soul; after all, the Soul Arts' primary purpose was to understand and manipulate the soul in ways that would baffle the average Divine.