Within the various corners of Cosmoria, there exist environments where the standard laws of physics simply do not apply. With technological advancement, the perspective of these regions changed, from divine things worthy of worship to objects of study. Despite the now-formalized study of these regions, the supernatural descriptor remains. Spirits are stable regions of space made up of noospheric radiation. In other words, they are disturbances in mental space that, as per the laws of physics, also disturb physical space.
Technically, all Minds or souls are spirits, but a living being's spirit is tethered to the brain and disappears upon death. A proper spirit is its own brain—a spirit does not need one because it keeps itself stable. The power of a spirit is limited only by its willpower, which means they range from inert point-like particles to god-like entities.
These beings have been tremendously influential in history. Whether as conquerors or prophets, spirits are as much a part of history as any normal intelligent being. The Naidarans are a "species" of semi-corporeal spirit and usually the only window into the world of spirits for the average person. They have played a great role in the history of Aylathiya, which has a far higher concentration of spiritual activity than most places.
Esoteria
Esoteria are a special class of spirit derived from Cosmoria's planes. A plane is a representation of a certain arbitrary concept determined at the dawn of the universe. Every intelligent being can understand these concepts (so long as they have a spirit within). Some of these planes, such as the Daegami, are themselves intelligent. They rule Azurullya.
Harmonic Thaumaturgy
Main Article: Harmonic Thaumaturgy
Harmonic thaumaturgy is the practice of deriving power from Spirits usually as a quid pro quo arrangement. Patrons essentially provide a portion of their strength to allow a host to perform greater feats at less cost. They can also provide access to thaumic abilities to those who would otherwise be unable to use thaumaturgy.
Shamanic Thaumaturgy
Main Article: Shamanic Thaumaturgy
Whereas harmonic thaumaturgy is about forging contracts with spirits, shamanic thaumaturgy is about coercing them. Through entry into a trance state, a shaman, can void their minds enough to host a spirit within. Most spirits are inert and useless, but the small number with a great deal of willpower can be harnessed for energy, thaumic power, or any other purpose. The main risk in shamanic thaumaturgy is when one encounters a truly powerful spirit, one whose will can override that of the shaman. At this point, the spirit is said to have possessed the shamans body. Many simply leave since they have no use for a physical form, but some choose to remain.
Spirit Possession
A spirit usually has no reason to take over the brain of a living being. However, in particularly vulnerable states, a living being may accidentally entrap a spirit. This is the current theory as to how consciousness evolved, how a creature made of atoms could somehow also have a mental aspect. A sufficiently intelligent (but not truly aware) creature unwittingly captured a spirit. With the evolutionary advantages of consciousness so pronounced, it makes sense that conscious life has evolved on so many worlds and in such a staggering array.
There is one species to violate this rule, the Dotsk. Having developed faster than the first spirit possession could take place, they evolved a "brute force" approach to intelligence. The Dotsk have tremendous willpower, but are arguably no different from animals. They are in the process of truly becoming conscious. About five percent of the species has come to host a mind, whether inherited from parents or captured from passing spirits. Belshazzar was an ancient machine which used Dotsk to intentionally capture and neutralize threatening spirits. The resulting army of potent users of thaumaturgy eventually broke containment and formed the Oberherr League who ruled Aylathiya for millennia.
List of Notable Spirits
This list is incomplete