The plane of existence that souls reside, also known as the soul plane, parallel but separated from the physical/material plane, like 2 sides of a page.
Souls can only interact with the material/physical plane by forming a soul connection between the planes. This seems to be the basis of conscious life. The strength of the connection is called Life Force or Vigor, a type of energy that exists between the planes, concentrated at the connections, keeping it open.
Through these connections, the soul can affect the physical plane, and vice-versa.
The soul contains a conscious and subconscious part, the conscious parts directs actions and deliberate manipulations, while the subconscious parts maintain the connection and affect the body in a million subtle ways.
The mechanics and how physics work in the soul plane is entirely up to world building, only the connection mechanics are necessary for this system of magic.
There could be soul cities, soul societies, cosmic divines, deities and horrors, the connections with the physical world might actually just be a very small sliver of Etherea. We can only observe the soul plane through these connections, what’s beyond is unknown, and may be unknowable.
