Mists of Shadow Moor
Magic works differently in the dark and terrible lands called the Baronies, mostly due to their dissociation from the other planes. The Baronies are encircled by the Shadowfell and tangentially touching upon the Ethereal Plane. A terrible gloom leaks into the land from its two neighbors.
This position gives the Baronies several persistent traits.
The Plane of Dread touches all magic, even in insignificant ways. Many spells have cosmetic changes to them; as though to remind everyone that magic is the pawn of the Dark Powers. For example, someone restored to life by a revivify spell might scream as though waking from a horrible nightmare, while a summoned mage hand or phantom steed appears skeletal and chilly to the touch.
By will of the Dark Powers, the sun never fully shines. Even during the day, the sky is dimmed by fog or storm clouds, or the light is strangely muted. During the hours of night, the land is particularly dark; light sources barely penetrate the gloom and undead stalk the shadows.
Natural daylight remains “bright light,” yet it isn’t considered sunlight for the purpose of effects and vulnerabilities. All other light sources, magical and mundane, halve their effective radii. Even darkvision functions at only half range.
Thick fog blankets the melancholy moors, confounding travelers and concealing hidden dangers. Vapors creep along the ground and around the headstones in graveyards, and other dark places. In the Baronies, mists seem to have a life of their own, infused with the power of the neighboring planes and serving the dark powers hidden within.
The mists of this land serve primarily to limit travel. It is easy to get lost within them, sometimes for days on end. And the danger is not limited to becoming lost; wanderers occasionally pass into the Shadowfell through areas called “shadow crossings.” Typically, those who wander the mists simply find themselves emerging somewhere close to the area they entered, no matter how far or long they traveled.
Even travelers determined to navigate the fog can find their way barred by the thickest mists, which exude a powerful, choking toxin. No magic or training can protect the living from this poison. Neither can normal or magical winds penetrate or move the choking mist. Even teleportation and divination magics cannot pass or scry across such mists; no one knows what secrets lie hidden in the heart of this unholy fog.
The thickest mists constitute heavy obscurement (see “Vision and Light” in the Player’s Handbook, chapter 8.) A creature that starts its turn in the fog must succeed on a DC 20 Constitution saving throw or gain one level of exhaustion (see appendix A in the Player’s Handbook). This exhaustion cannot be removed while the creature remains in the fog.
The position of the Baronies near the Ethereal and the Shadowfell, and its separation from the other planes, has deep implications for cross-planar activities like summoning.
Magic users in the Baronies can only reach two other planes of existence. They can access the Border Ethereal, a land of restless spirits and landscapes shaped by the lingering passions of the living. (The Deep Ethereal remains out of reach.) When leaving the Border Ethereal, travelers are pulled back into the Domain of Dread.
Characters in the Baronies can also reach the Shadowfell, but usually do so unintentionally by wandering through shadow crossings. Even magic that would create or access demiplanes or pocket realms simply fails.
Magic that communicates across planar barriers always fails. Magic that would summon beings from other planes either fails or it brings magical or mundane creatures from the Shadowfell (or from elsewhere in the Baronies) if approximate targets can be found. The results are somewhat unpredictable. And magic that would banish creatures to other planes either fails or it relocates the target to somewhere else within the Baronies.
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 requires a DC 30 insanity check to avoid suffering Indefinite Madness brought on by the realization that its spirit is trapped in the baronies, likely forever.
The Walking Dead
The souls of the dead are as trapped in this land as are the souls of the living. When a humanoid that has been dead over 24 hours somehow returns to life, the realization of the soul’s immobility invokes a Nearly Impossible (DC 30) horror check. (See the Fear and Madness page.)
At night, undead creatures gain advantage to resist any Channel Divinity powers that allow a saving throw. This penalty also applies during the day in rare, unhallowed areas called “pits of evil,” unless the pit is in an area of direct, natural sunlight.