Island in the Mist
The Mists appeared instantaneously in at least 126 of the known 227 known planes of existence in YD 4444.
A number of theories exist as to why the Mists appeared. Most non-Cassian magical scholars tend to believe it was the misapplication of Cassian portal magic. In Cassian schools, they teach that the Mists were created by The Aechmus Brothers. The Elves believe that the Mists were created by Sherylin. There is evidence of a few primitive tribes worshiping the Mists as either a gift or a punishment from their Gods. Most modern societies just treat the Mists as a permanent natural border to their land.
The Mists get their name from the light fog that is visible in every direction throughout the area. The fog appears to be enchanted water vapor, though it was decidedly not created using the same magical thread that the humanoid and elemental peoples operate with. Although the Mists tend to reside over forested areas, it seems that they can just as easily rest over desert, plains and mountains.
Those entering the Mists tend to experience a vague feeling of disorientation. Those who lose sight of the point where they entered the Mists become lost almost immediately, and have no way to return to where they came from. Although the experience is different for everyone who travels through the Mists, most travelers report landscapes that periodically alter themselves whenever they stop being observed.
There are many dangers and oddities within the Mists. Creatures of all varieties travel through the Mists, some monstrous, some magical, some fearsome. Ruins of civilizations long forgotten are also spotted throughout the Mists.
Land that is free from the Mist is called a “pocket.” It is unknown how many pockets there are, though the nation of Cassia has colonized more than 700 already-inhabited pockets. Strangely, the Mists have seemed to avoid settling over most populated areas and cities (although there are exceptions, such as the sad case of Upper Blakenshire).
Characters who enter the Mists must make a Survival check (DC 25) every minute. Those who make the check may turn around and return to the pocket from which they left; those who fail the check become lost for 4d4 days. When traveling in groups, this duration increases by one day for every three people in the party. If the party changes course, the timer is reset. At the end of that time, the lost party arrives at a random pocket (as determined by the DM) within The Mists.
During that time, the character is subject to any and all random encounters that can happen in The Mists. Characters who are separated from their parties by more than 90 feet must make an additional Survival check or lose their party entirely.
Special: Elves use special rules for navigating The Mists.