The Xil, like the Suul, were created in the first moments of the universe, but they consist of Ye (magic) only. They are usually associated with random chance and mischief.
Once the Suul began to have offspring (the Meyelu and Beyelu) the Xil, who cannot reproduce, were terrified that they would be overwhelmed by the Immortals. In an effort to discover their opposition’s weakness, they kidnapped Mowolon and inadvertently drove him mad.
Bol punished the Xil by forcing them to collect the souls of the newly dead and deliver them to the underworld; this remains their responsibility to this day.