The shamanic perspective of heaven and the underworld alludes to shifts of consciousness, which the Abassi enable a shaman to experience. Heaven refers to a shift of consciousness above the (cerebrum) head, where the shaman will sense he is flying up into, and through, a vaginal star barrelled tunnel into another planetary (parallel universe) sphere.
As for the underworld, it refers to a shift of consciousness to the (cerebellum) back of the head, where the shaman experiences falling backwards into a great void before attaining ingress into the (alternate Earth’s/eternal-reccurrence) ancestral spirit world. Basically, the Abassi enable (hypnagogic) trance ingress into both (brain) domains.
The Yakut generally have two types of shamans, the black shamans, whom interact with the Abassi, are called, Abassy-oïuna, and the white shamans, who are called Aïy-oïuna, do not do so. The ‘black shaman’ among the Yakut bares no comparison whatsoever to the Western counterpart of an Abrahamic Satan worshiping black magician, since shamanism is not a dogmatic religion, it is a system of techniques, which enable consciousness expansion.
https://faustuscrow.wordpress.com/2014/09/07/succubus-spirit-wives-of-the-yakut-shaman/