Inner Plane

The Inner Planes are the fictional innermost planes of existence in the standard cosmology of the Dungeons & Dragons role-playing game. They are the building blocks of the multiverse, the elements and energies from which all of the material universe (the Prime Material Plane, or, in the 3rd Edition, simply Material Plane) is made.

The Inner Planes, the material building blocks of reality and the realms of energy and matter, stand in contrast to the intangible and esoteric Outer Planes, which include the realms of ideals, philosophies, and gods.

The Planes serve as a home for extraplanar creatures which magic-users can summon. High-level adventurers can quest on the Planes, which are usually dangerous without protective magic.

In the first edition there were initially four Inner Planes, consisting of the four classical elements of fire, earth, air and water, as well as the energy planes of positive and negative material, and the ethereal plane.

In Advanced Dungeons & Dragons 2nd edition, the Inner Planes intersect each other to produce a number of other Planes. Probably the best analogy describing their relationship to each other is that of an octahedron: the northern pole is the Positive Energy Plane, the southern pole the Negative Energy Plane, and at the middle four points lie the Elemental Planes (based on the four classical elements): Air opposite Earth, Fire opposite Water. They were an important part of the Planescape setting. Each edge is also either a para-elemental or quasi-elemental plane of its own.