The Otherlands

Not so much a single plane as many, the Otherlands is the collective name for many small realities that float suspended in the Evernight. Their distance from the material plane varies, and the further out a part of the Otherlands exists the harder it is to reach via magic. The nearest portions are populated by lesser demons and spirits, while the farther reaches hold the domains of the most powerful and otherworldly beings.

Physical Qualities

A patchwork of many scattered, distinct glimpses of reality, the physical properties of the Otherlands vary wildly. Each distinct portion is generally tailored to the desires of the being that created it. While some resemble environments found in the Old World or Genesis, this is by no means a rule and there are plenty that are entirely alien in appearance with similarly alien rules when it comes to their effect on time, distance, gravity, and other physical laws.
The size of domains within the Otherlands is similarly varied, and few are large enough to exist as entire worlds; they're typically more similar to the individual shards of Genesis, ranging from tiny areas only a few hundred feet across to areas that can be thousands of square miles across. The borders at the edge of pieces of the Otherlands typically are a sharp cutoff, with the land falling away and making it clear that they exist as free-floating landmasses in a void, but some have magical barriers and convoluted illusions to give the impression of a more natural space.

Access

The domains of the Otherlands are accessible with the use of magic, and their inhabitants are often the subject of summoning magic practiced by Binder and Caller mages. However, it's possible to travel there physically as well by reverse-engineering these same forms of magic to travel physically to the location of the being targeted. Travelling the Otherlands is a risky proposition due to the powerful and often hostile nature of its inhabitants, but a skilled mage can also benefit from a place where magical strength and talent can shape entire worlds.
The limiting factor of a mage's ability to access the Otherlands is the concept of 'pressure'; the further from reality one strays, the heavier the weight of the Evernight's unrestrained magic bears down. As a result, there are many places in the outer reaches of the Otherlands that are simply beyond mortal reach. Many of the more powerful demons and other beings with no wish to be disturbed live in this zone; weaker beings live closer to reality, and are subject to mortal intrusions as a result. While mortals can try to delve into the outer realms of the Otherlands, ambition can easily turn fatal. Reach too far with natural magic, and the mage's lifeforce can collapse under the strain.
The realms where the gods dwell, located exponentially deeper in the Evernight than any other portion of the Otherlands, are completely beyond the ability of even the most foolhardy. Mortals can only reach these when brought there directly by the deity in question.

Rulers and Inhabitants

The beings of the Otherlands vary wildly, and each domain will have its own hierarchy of power. Some areas may only be home to a single inhabitant, while others host whole populations generally ruled by the strongest. Like all things in the Otherlands, who rules from day to day isn't a fixed thing. Since the vast majority of what lives in the Otherlands are demons , it's a very dog-eat-dog world... or rather demon-eat-demon, which is often an extremely literal description. Many less powerful demons too weak to form their own domains live in communal spaces in the near Otherlands, which are theorized to have formed organically or have been abandoned by past inhabitants as they drifted too near the border of reality
As a general rule, most beings of the Otherlands have little interest in domains other than their own; there's little need to conquer territory when those powerful enough to do so can simply create new land straight from the void. The most powerful beings are those who dwell in the far outer reaches, and are usually demon lords whose power begins to approach those of the lesser gods; they have the strength to create vast domains from the available raw energy, and prefer to do so at a depth that gives them a far greater degree of control over their surroundings and makes it harder for ambitious Binders to reach them. The Immortal Flame that the Seraphs worship is the most famous example of this, but is far from the only one.
Similarly, the raw energy and darkness of the Evernight that exists between the distinct realms of the Otherlands has its own population. Loosely ruled by powerful beings such as the Blood Gods who have no real desire or need for the comfort of reality, it's also populated by beings who are too weak to create their own domains but have found themselves driven out of the existing spaces available to them.

Quick Facts

Inner/Outer Spindle: outer
Magic Saturation: varies
Governed By: varies
Reachable: yes