The method is simple: an otherworldly being must behave as prescribed by its rank until the power becomes part of it. 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 influence: the Lawyer speaks for others and knows the value of a word, the Briber finds that value in everyone, the Count of the Fallen rules those who have already agreed.
The method long remained the knowledge of the few: church hierarchies were in no hurry to reveal it, and many otherworldly beings ascended blindly, paying for it with their sanity.