Are Shaman only in certain cults (Daka Fal/ Waha) or do all cults, specifically Orlanth, have them too?
It depends. In many cases, a shaman is initiated outside of the main structure. So in Theyalan and Pelorian cultures, most shamans are “hedge magicians”. They were initiated by another shaman or even by a spirit.
Many cults will allow shamans to initiate to the cult, but many of these shamans refuse.
In other cultures, shamans are a key part of the main cult structure – so for example, in Prax or among the Hsunchen or Doraddi. Here the shamans were initiated within the cult structure.