No Escape

Everything living (and dead) is trapped within this planar prison. Only the Vistani have the ability to navigate The Mists successfully.

Alterations to Magic
No spell (not even Wish) allows one to escape from Ravenloft. Astral projection, teleport, plane shift, and similar spells cast for the purpose of leaving the demiplane simply fail, as do effects that banish a creature to another plane of existence. These restrictions apply to magic items and artifacts that have properties that transport or banish creatures to other planes.

Magic that allows transit to the Border Ethereal, such as the etherealness spell and the etherealness feature of incorporeal undead, are the exceptions to this rule. Any creature that enters the Border Ethereal is pulled back into Ravenloft upon leaving.

Magic that summons creatures or objects from other planes functions normally (summoned beings/items become trapped within the demiplane, and are unable to return home), as does magic that involves an extradimensional space.

While in Ravenloft, characters who receive spells from deities or otherworldly patrons continue to do so. In addition, spells that allow contact with beings from other planes function normally- with one proviso: Dreadlords can sense when someone in their domain is casting such a spell and can choose to make themselves the one who is contacted.

Resurrection Madness
In Ravenloft, the souls of the dead are as trapped as the souls of the living. They become caught in the mists and can't travel to the afterlife. When a humanoid who has been dead for at least 24
hours returns to life, either by way of a spell or some supernatural means, it gains a random form of indefinite madness brought on by the realization that its spirit is trapped in Ravenloft, likely forever.

Souls and Shells
The people of Ravenloft are made of flesh and blood. They are born, they live, they age, and they die. But not all of them have souls. When a being with a soul dies, that soul remains trapped until it is reincarnated in a newborn. It can take decades for a bodiless soul to find a host, and individuals who share the same soul over generations tend to look alike. All of the Vistani have souls of their own.

Although the soulless are physically indistinguishable from those with souls, they tend to be bereft of charm and imagination, and to be more compliant and depressed than the others. They are maudlin folk who experience fear but neither laugh nor cry.

Vampires, and similar "life-essence" feeding creatures, can only feed on those who have souls, they can't draw any nourishment from the soulless. These creatures can tell at a glance whether someone has a soul or is merely a shell.

No Escape

Ravenloft: Curse of Strahd bigwhiskey74