Energy Planes
The Energy Planes are part of the Inner Planes of Dungeons & Dragons, lying adjacent to the Elemental Planes and considered by some to be part of them.
Like the Elemental Planes, the Energy Planes represent the fundamental forces of creation; Positive Energy and Negative Energy, or, more simply, Life and Death. This makes them amongst the most featureless and hostile planes in the entire Planescape cosmology, as the former overloads your body with energy until it disintegrates from the strain and the latter flat-out kills you.
The Energy Planes are best known for their "fusions", the Quasielemental Planes, which are born of the meeting of an Energy Plane and an Elemental Plane.
The Positive Quasielemental Planes consist of Lightning (Positive/Air), Mineral (Positive/Earth), Radiance (Positive/Fire), and Steam (Positive/Water).
The Negative Quasielemental Planes consist of Ash (Negative/Fire), Dust (Negative/Earth), Salt (Negative/Water) and Vacuum (Negative/Air).