Lorekeeper
Welcome to the Nexus! This is a unique realm that exists between the worlds. Connected to many, where you can find many unique creatures from many worlds and many realities. An eldritch realm, otherworldly and mysterious.
The Nexus is often called the Realms Between, because it is a collection of realms existing intertwined between the layers of Reality. A realm full of strange beings, creatures that are extinct elsewhere, the magic of many realms mixed into one.
There are several worlds connected to the Realms Between by portals that can be found in ancient arches, either natural or built, if old enough.
The symbol of this creature can be found around the portals and doorways, and some can even embue doors with the power to go from one dimension to the next.
The Realms Between consists of several realms, or layers, some so deep they nearly touch the Void itself. Many strange eldritch forces travel through this world, and those who have learned how it works can use it to travel from world to world. The Realms Between is vast beyond all imaginations, and anything can happen within it. The very rules of Reality bend and shift and change.
The most commonly used Realm in the Between is the Mirror World. The Mirror World is an ever expanding realm, simply known as the Mirror. Everything that has been reflected and observed has a chance of being copied as a reflection of that moment in the Mirror World. It will remain there as it was reflected, empty and mysterious, for all time. No animal life, no real weather, still and silent. The Mirror world has many things preserved, from cities, to temples, to pristine wilderness. It is said that a world that is soon to end will be reflected here to be preserved. The Mirror World seems to be an entity of its own, almost living. Some of you may have even travelled through it unintentionally; have you ever been walking through the woods, and everything suddenly went completely silent and still? And everything felt... strange? Have you ever gone into a town, only to see everthing mysteriously empty without a soul around? Or gone to the remains of an old ruined town, only to see it as it once was, still and silent? Then you have likely passed through the Mirror without realizing it.
Many Gateways lead into the Mirror World, and if you can get to a reflection of another world, you can use that to direct you to the world the reflection came from. There are many connections between worlds within the Mirror as well. Even if you go directly from one world to the next, you are passing through the Mirror.
Many maps of parts of the Mirror World exist, with ways to get from place to place, where doors and portals are, and there are some who have traversed and explored it for ages.
There is also The Between, the realm that exists on the edges of reality, infinite and strange. The entire place has breathable air. How? Nobody knows. It just is. Things here do not make sense. The Between is inhabited by many strange creatures, including the wild and powerful Kivuuli that uses it to traverse from world to world through rifts that open and close naturally.
Imagine the air around you, full of bubbles. Now imagine that each of these bubbles is its own dimension. It's own universe. Has its own laws, and inner workings. Now, imagine all the space between the bubbles. A strange place, between the dimensions; ever shifting and changing. The rules of physics do not apply; great islands of stone float through the darkness, covered in forests of strange bioluminescent fungus-like plants and other strange flora. Inhabited by strange creatures of all shapes and sizes, from tiny glowing dragonlike lizards to massive beasts that would put Earth's dinosaurs to shame. Literally anything can happen in Between, any sort of creature, any world, any dimension, any universe. The Kivuuli can reach many worlds and some may act as guides to help others travel through this world.
Harsh, but oddly beautiful, Between is buzzing with strange power and magic and the magical rules and laws of hundreds of dimensions, worlds, and universes clashing together in beautiful chaos. The areas of Between are effected by the laws of the dimensions and worlds closest to them; making Between highly varied. Between is beautiful; but as beautiful as it is it is deadly.
There are also some spacefaring races that have used this unique realm to get from place to place.