The Feywild
The Feywild is a nearby plane of existence of unusually potent magic. Its geography is similar (though not identical) to that of the moral realm, leading some sages to conclude that it is an echo of the Prime Material Plane. Some ancient elven texts, claim the reverse is true: that the Feywild is the true existence, and the duller mortal realm a mere reflection. Some elven legends claim that the elven people originated in the Feywild, though this is not universally accepted.
While in ancient times the boundaries were more easily crossed, the moral realm and the Feywild have drifted apart over the millennia. Fey crossings still appear under certain conditions in certain places, but stable doorways are immensely rare and coveted.
The Feywild is inhabited by many creatures, in particular the Fey, otherworldly beings with some intrinsic connection to magic, nature, or both. The Fey, chaotic in nature, are bound by a complicated web of custom, magical law, and ancient agreements that can render their behavior and desires incomprehensible to inhabitants of the mortal realm. The only constant is that a properly made deal must be adhered to by both parties, though the Fey are notoriously tricky bargainers. The Fey do not worship mortal gods and do not value mortal lives, though some find mortal beings particularly entertaining (as a human might observe an animal), interesting (as a collector enjoys a work of art), or repugnant.
Other inhabitants of the Feywild include elves, the eladrin, hags, nymphs, sylphs, dryads, pixies, satyrs, centaurs, certain subspecies of goblinoid and giant, and other, stranger beings.
The Feywild is ruled by the Archfey and a variety of lesser Fey lords and ladies. Even minor fey nobility are beings of immense power, and the Archfey are akin to deities. They rulers of the Feywild are enmeshed in constantly shifting alliances and millennia-long plots, making political engagement perilous.
The Fey are particularly hostile to fiends, beings of the Shadowfell, and creatures of the Outer Dark.