An imp familiar to the wererat Longtail
After arriving on what the player’s refer to as the material plane Achsyyx found an exit from the Prison of Sorrows and proceeded to con the wererat Longtail into entering the prison and opening a portal into his origin. After things started going his way the player characters arrived and made short work of his portal.
Achsyyx fled from the battle when he saw that it was lost. One thing is for sure though, Achsyyx may be the only living soul that knows of a way out of the Prison of Sorrows.