Coloquially known as 'magical composition', this is a body of kheji surrounding the soul that forms the core of an entity's relationship with kheji. It is made of dense kheji, though not as dense as that of the soul's. One's nientak determines traits such as Lumen or Vesper casting ability, traits such as jufataxen, and way the entity's kheji manifests.
The nientak is almost impossible to fully destroy and like the kheji that forms the body, can slowly regenerate itself. This differs from the soul, also known as the nihas, which is unable to regenerate.