The Myst

The Myst is a primal force of pure chaos that predates both our world and even the gods themselves. No one knows where it came from, or how it works, but everyone knows that it is dangerous, powerful, and to be avoided unless you want to find yourself far from home, face to face with the unknown.
The Myst has many forms, but often appears as a shifting fog whose colors shimmer and swirl like oil on water - iridescent purples, greens, and blues dancing through the white. It rolls like an otherworldly dancer, coiling and unfurling in patterns that seem almost deliberate. Those who have survived close encounters with the Myst speak of how it seems to respond to their presence, reaching out with tendril-like wisps that dissipate when approached.
A huge ring of Myst surrounds the whole of Caelwhyn, along the edge of the firmament, acting as both a barrier and a gateway. It marks the edge of our own known world, and legend has it that if you travel through it, you could reach new worlds much more mysterious and wondrous than our own... or you could be stuck within it, wandering endlessly. Some sailors tell tales of ships that strayed too close to the Myst, only to emerge years later with crews who hadn't aged a day.
For Caelwhyn is just one world within the Myst, and the only mortal one we know of. Others exist beyond the fog, realms of immortal beings where different rules hold sway. The most prominent denizens of these are known to mortals as Great Spirits, beings of immense power and varied nature. Some Great Spirits take great interest in our little mortal world, and oversee fundamental concepts like love, death, or the harvest, while other smaller ones may simply act as guardians over specific groves or wells etc. Some were once mortals who ventured beyond the Myst and ascended to a higher state of being, like the legendary King Hjoldar of the dwarves. Others are ancient and mysterious entities who maintain their own domains beyond the Myst.
Unlike The Lumeni - the gods who created our world - the Great Spirits do not form a unified pantheon. They are countless and varied, each following their own inscrutable purposes. While the Church of the Lumeni advises caution in dealing with these beings, many still seek to interact with them, leaving offerings for day to day blessings. In extreme cases this can lead to the sorts of pacts that empower warlocks.
Not all beings that dwell within the Myst are divine or benign. Monster hunters track Myst activity closely, knowing that where the fog thickens, horrors often follow. These entities range from wholly alien beings that defy description to twisted, corrupted versions of natural creatures. The most experienced hunters learn to read the subtle signs of Myst manifestation - unusual color patterns in the air, unexplained cold spots, or the strange behavior of local wildlife that often precedes a dangerous emergence.
The Myst is not content to stay at the edges of our world - it can appear anywhere in Caelwhyn, particularly in places of deep ancient magic. When the Myst merges with divine light, it creates what we know as magic, and a small percentage of people can wield and manipulate this force to cast spells. Some scholars theorize that the Myst contains all possibilities and concepts in an intangible form, and when divine light touches these concepts, they become tangible and real, turning thought into reality, creating magic.
The Myst remains one of the fundamental mysteries of our world, a force that both threatens and empowers us. While the Lumeni brought order to Caelwhyn, the Myst reminds us that chaos and possibility lurk at the edges.