Ravenloft: Generations of suffering
Once in a great while, the lands of Ravenloft replace large portions of land in other realms. This is called a Conjunction. It may be the one time that creatures who are native to Ravenloft can leave their shadowy realm. Even lords, such as Strahd, may be able to escape the borders of their domains. Currently, no lord has taken this step, though the reasons why are not fully understood.
The mists might not be visible or active when a piece of Ravenloft joins another realm.
Throughout time, only a few conjunctions have been reported, and some of those are suspected to be unrelated phenomena. So few have occured that it is meaningless to speculate how long any future conjunction might last, or where it will appear. All that is known is that they do end in time, disappearing completely.
Many of Ravenloft’s powerful lords hope to learn the secrets of the conjunctions. They seek to cause another conjunction to occur, to either escape their domains or to extend their sway beyond the shadowy realm in which they reside. None have succeeded in this quest.