The Otherworldly must behave as their level prescribes, until the power becomes part of them. Until the potion is digested, the carrier is vulnerable: the power is already there, but there is no control over it yet.
The roles of the craft path: the Apothecary prepares concoctions and understands compositions, the Beast Tamer lives among animals, the Potion Professor turns the craft into science.
The method long remained the knowledge of the few: the church hierarchs were in no hurry to reveal it, and many otherworldly beings rose blindly, paying for it with their sanity.