Shadow Forest is a no man's land. It is an area where creatures made of shadow magic roam and hunt anyone who enters it. Many people have tried to tame the forest, but all failed.
Stories tell of creatures made of dark smoke and shadows who are almost as tall as trees. People who survived ventures into the forest tell how these creatures chased them and how they devoured anyone they caught. According the stories, humans devoured by one of those creatures turn into what people started to call "Shadow Ghosts". The ghosts are smaller and faster than the giant monsters.
How the forest became the living place of shadow monsters is a mystery. Some people claim that it is a natural phenomenon, while others suggest work of a curse. Lack of mentions of the Shadow Forest in surviving elven texts makes the research into its origin even harder. One of the more popular theories connects the forest with the mentions in elven texts which link shadow magic to the fall of the elven civilization. According to this theory the Shadow Forest is a remnant of whatever killed the elves.
Shadowburg is castle at the Esterian border of the Shadow Forest, but it is manned by soldiers from the Queendom of Esteria, Inherited Empire and other countries. The castle is located at one of the main entrances to the forest and its garrison is tasked with watching for possible attacks by shadow monsters. Such attacks are very rare, but their possibility makes everyone nervous.