The job description
Ethnographies describe specialists healing, divining, settling disputes, advising hunters, conducting funerals, interpreting dreams, holding oral history and performing publicly. The role is practical before it is mystical.
Ambivalence
Those who can cure are often believed able to harm. Accusations of sorcery follow the same people who are consulted for help, and this ambivalence is structural rather than incidental.
Payment
Gift, obligation, fee, patronage and, more recently, retreat pricing. Every economy shapes the practice it funds.