shamanism is not (actually) a mysticism.

Shamanism is simply a way of tapping into a fuller potential of the evolved human mind. It is not a mystical phenomenon in the narrow sense of that term -- although many of its practitioners have described it that way, in the past. The reason that descriptions of shamanistic experience so easily lend themselves to a mystical way of talking is that the fundamental shamanistic encounter is with a part of the brain that developed prior to humans developing the capacity for language. So, when one descends to this part of the brain, the range of experience is nonverbal -- there are simply and practically no words for it.

Since that is the case, a shaman will have difficulty conveying what his area of practice is, and will be easily dismissed in a pejorative way as a "mystic". But, as I have explained, the lack of language for the shamanistic experience pertains to the particular neurobiological structures of mind that inform this shamanistic experience. Shamans are not mystifiers but demystifiers of this part of this primeval part of the brain, and its form of consciousness.

Secondly, shamanism cannot simply be tapped into as a form of intellectual knowledge. Rather, a shaman conditions their mind in the same way as a martial artist conditions the mind and body. The essence of the shaman's power is her mastery of her reflexes, which enables her not to react to all sorts of events that assault her mind at a subliminal level. By not reacting, she frees herself from various devices of social control. Fundamentally, she has learned to understand her own preverbal mind and its reflexes so well, that she can master them, overriding or redirecting certain reflexes, rather than resorting to heavy-handed techniques such as repression.

This is the meaning of shamanic mastery and self-knowledge -- but it is founded on experience, and this experience itself has a scientific grounding.

We would be wrong to attribute what I have described to something nebulous sounding, like "mystical experience" -- although one might at times use such a term, as Bataille does, to make a rhetorical point.