The Realm of Spirits

The divine battles that ended the Hollow Wars greatly twisted the magic of Asuvia. An "in-between" was created, a realm where the souls of the dead could linger without passing into The Raven Queen's domain, alongside celestial beings. 

The Spirit Realm mirrors the Material Plane in some ways. It is not a complete plane, but seems to exist in pockets and bubbles, contained within themselves with bridges between. Some spirits may have an entire territory to themself, while others may build facsimiles of cities, complete with places of business and entertainment.

It was once believed that the Spirit Realm may have been an altered Feywild. In more recent times, it is speculated that instead it is the result of the Celestial Plane bleeding into the Ethereal. Being part of the Border Ethereal, the Spirit Realm regularly overlaps the Material Plane, allowing spirits to slip through or influence the world beyond, or whisking mortals away. Certain times, such as during The Ghost Festival and Serien's full moon, draw the Spirit Realm even closer. During these times, spirits are able to more easily move between planes.

Geography

The Spirit Realm does not abide by the same physical rules as the Material Plane. It is broadly divided into two types of areas: Vital Domains and Isolated Domains.

Vital Domains

Broad swathes of land within the Spirit Realm, speculated to be functionally infinite. These domains have no central ruler, instead providing a home to any spirits that find themselves suited to the environment. Typically minor spirits will carve out lives for themselves in both solitary domiciles or communities. Others may only pass through.

These domains can still host powerful spirits, though they will only command a chosen zone instead of the entire domain. As a result, vital domains can be the background of territory disputes and lack the longterm stability that isolated domains possess.

Vital Domains connect to one another and can grant access into certain isolated domains.

Isolated Domains

These domains are defined by the spirit that rules them. They are formed around their host spirit as a lair, and are characterized by that spirit's nature. These domains have broad variance in their size, appearance, and nature. Some spirits can exercise precise control over their domains while others simply call it home. Some may be aware of all denizens of the domain and can exercise influence over those within.

If a host spirit is removed from their domain or killed, the domain will fade. In some circumstances, another spirit has been able to claim the space as their own and become its new host.

Spirits

The denizens of the spirit realm are unlike those of other planes. Both celestials and the spirits of the dead find themselves altered, taking new shapes and gaining new powers. There is not much of a classification for the forms they take, most seeming to be unique to the individual.