Jardis

Type: Disease
Jardis is a supernatural affliction that affects the specific powers of Supernaturals, causing their abilities to activate suddenly with no warning and at seemingly random intervals. A Firebringer suffering Jarvis would be perfectly fine one minute but then burst into flame the next, without ever having summoned that power of their Order. 
Adepts suffering Jardis are walking infractions of the Discipline Arcani, since their powers could activate of their own accord at any moment. Jarvis normally runs its course in about a week and once you have it, you're immune afterwards. 
Members of the Order of the Unknown are not affected by Jarvis in any noticeable way, all their powers are vague and abstract anyway.