The Ashen Priestess is a name given to Heroes who serve the gods, allowing them to be used as vessels to create miracles.
Power Level 
As a healer, this name can be used to prolong battles indefinitely through casting miracles on soldiers, healing all non-mortal wounds. It has can also be concentrated on one individual ally to create instantaneous regeneration.
The role of the priestess is to care for those in need. They are drawn to help other and to serve the will to their gods. It is noted by Hanno that the Ashen Priestess lacks the warm bedside manner common to priest.
The priestess power works differently than mages, as remarked before by Zachariah. They do not rely on their own reserves of magic to cast spells but rather they are given power by the grace of gods to cast miracles. Priest mainly employ this power to heal the injured Ashen Priestess. This ability is also able to use built up dust around herself to both attack others and defend herself.