You have to go by definitions given by others until you come to experience it yourself in meditation.
Developing high level clairvoyance and a clairsentience would also help I believe.
In the meantime :) a study in comparative religion with an occult understanding can be eye opening for sure.
Wuji or Kung is Infinite Void so that would be even higher than the Soul (or Higher Soul, which acts as an intermediary between the two). It would be Ain in Kabbalah understanding and The Monad or Paramatma in theosophy/oriental teachings. It is pure energy without form.
According to classic occult teachings the Soul cannot be entropic since it is an individualized reflection of the Divine in you, which in its trifold manifestation is in essence Love, Wisdom and Power
(or Vishnu, Brahma and Shiva / Son, Father, Holy Spirit).
The more you connect to the Soul in you the more these qualities are manifested. It is your consciousness, the observer in you. It must be negentropic in nature, as it is not constrained by time (or space), it is the body/mind complex (lower bodies, of which the human spirit is part of) that is, therefore subject to entropy… so that’s where you target plasma.
Generally speaking I think we could say that the more you realize that you are the Soul and not your body or your mind, which are just vehicles, the more coherent or wholesome you are (meaning… negentropic).
Also by extension the opposite must be true.
Just my 2c anyways (I still don’t have direct experience for the most part), I’m not a teacher or anything like that nor would like to be lol. In any case, if you are interested in these subjects there are some books I might suggest that have been an eye opener for me.