The Otherworldly must behave as prescribed by their stage, until the power becomes part of them. 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 tied to risk and stakes: the bearer puts the outcome on the line again and again and learns to live with what comes up.
The method long remained the knowledge of the few: church hierarchies were in no hurry to reveal it, and many otherworldly ascended blindly, paying for it with their sanity.
