The Shadow Realm
The Plane of Shadow is a dimly lit dimension that is both coterminous to and coexistent with the Material Plane. It overlaps the Material Plane much as the Ethereal Plane does, so a planar traveler can use the Plane of Shadow to cover great distances quickly.
The Plane of Shadow is also coterminous to other planes. With the right spell, a character can use the Plane of Shadow to visit other realities.
The Plane of Shadow is a world of black and white; color itself has been bleached from the environment. It is otherwise appears as a twisted facsimile to the Material Plane.
Despite the lack of light sources, various plants, animals, and humanoids call the Plane of Shadow home. However, due to the nature of the Shadow Realm, they have become dark and twisted over time. Proximity to some of these unnamed horrors, especially those that have been there since the beginning, can cause madness on sight, and other sickly twisted maladies.
The Plane of Shadow is magically morphic, and parts continually flow onto other planes. As a result, creating a precise map of the plane is next to impossible, despite the presence of landmarks.
The Plane of Shadow has the following traits:
Magically morphic. Certain spells modify the base material of the Plane of Shadow. The utility and power of these spells within the Plane of Shadow make them particularly useful for explorers and natives alike.
Enhanced magic. Spells with the shadow descriptor are enhanced on the Plane of Shadow. Such spells are cast as though they were prepared with the Maximize Spell feat, though they don’t require the higher spell slots.
Furthermore, specific spells become more powerful on the Plane of Shadow. Shadow conjuration and shadow evocation spells are 30% as powerful as the conjurations and evocations they mimic (as opposed to 20%). Greater shadow conjuration and greater shadow evocation are 70% as powerful (not 60%), and a shades spell conjures at 90% of the power of the original (not 80%).
Impeded magic. Spells that use or generate light or fire may fizzle when cast on the Plane of Shadow. A spellcaster attempting a spell with the light or fire descriptor must succeed on a Spellcraft check (DC 20 + the level of the spell). Spells that produce light are less effective in general, because all light sources have their ranges halved on the Plane of Shadow.
Despite the dark nature of the Plane of Shadow, spells that produce, use, or manipulate darkness are unaffected by the plane.