Prescyla Osiris inherited the position of Oracle under Krovo Scrios during the Extant War
The Oracle was a rank of the Savant Caste that effectively served as the heir-apparent to the Harbinger of the Charon Dominion. The second-in-command of both the Savants and the Charon in totality, the Oracle was groomed directly by the Harbinger to eventually be the Dominion's successive leader, should eventuality or happenstance lead to the then-Harbinger's death.
Like the Prophet of the Void, the Oracle was required to possess the rare Void power of Omen. Ideally, the Oracle chosen by the Harbinger was to possess a potential either rivaling or surpassing their own, so as to assure rule by the strongest.
On rare occasions, particularly powerful Harbingers would even be forced to cannibalize their own people through the usage of Consume, in order to extend their longevity until they could find a worthy successor.
Krovo Scrios inherited the position of Oracle from the extremely young age of nine, although he was not inaugurated into the position until he was sixteen. Prescyla Osiris was appointed as Oracle by the time of the Extant War, although Scrios considered her little more than a right-hand as opposed to an eventual successor.