The Otherworldly must behave as his level prescribes, until the power becomes part of himself. Until the potion is digested, the bearer is vulnerable: the power is already there, but there is no control over it yet.
The roles of the path are heavy in themselves: the bearer passes through states from which an ordinary person does not return, and must remain himself in each.
The method long remained the knowledge of a few: the church hierarchs were in no hurry to reveal it, and many otherworldly beings ascended blindly, paying for it with their sanity.