Demiplane

A demiplane is a fictional extraplanar location or dimension that exists independently of the prime material plane. Often, demiplanes are depicted as small, isolated realms, perhaps only a single room, a pocket of wilderness, or a specialized dungeon. They are typically created through powerful magic, divine intervention, or natural planar rifts.

The nature and accessibility of demiplanes vary greatly in different fictional settings. Some may be easily entered and exited, while others are hidden, guarded, or require specific keys or rituals to access. Their environments can be as diverse as any existing plane, ranging from barren wastelands to lush paradises, or even bizarre, abstract spaces.

Demiplane creators might use them for a variety of purposes. They can serve as personal sanctuaries, secure vaults, prisons, training grounds, or experimental laboratories. The isolation of a demiplane can provide a controlled environment free from the influences or interference of other planes or planar inhabitants. Some stories feature demiplanes that are unstable, slowly collapsing or expanding, adding an element of danger to their exploration. The concept allows for self-contained adventures and unique challenges for characters.