Demiplanes

According to the classic Drankorian text On Metaphysics, one of the foundational early texts in the study of extraplanar cosmology, a demiplane is “any extraplanar space, howsoever created and sustained, that is limited in duration, finite in space, or both.” While this concept is considered outdated by proponents of the Standard Multiversal Model, who consider only time-limited extraplanar spaces to be proper demiplanes, it remains useful to explain many planar phenomenon.

Students of magic will be familiar with spells and other magic that allow the creation of a temporary and dimensionally restricted extraplanar space. These limited effects, which often require continual mental effort on the part of their creator to sustain, are, according to On Metaphysics, best understood as temporary shapings of bubbles of extraplanar resonance that still echo from the upheavals of the Riving.

The Drankorian conception, however, considered space-limited but permanent planes to be demiplanes as well, and some modern scholars have sought to restore this definition. Under this model, extraplanar spaces such as the domains of shadow and dread collectively known as the Shadowfolds; the fragmentary and perhaps-apocryphal Mirror Realm; and the terrifying dream fragments of the so-called Nightmare Realm are all considered demiplanes, as although they appear to be largely permanent (despite tales of some domains of shadow being destroyed), they are restricted in space.