Description
The Demi-Planes are a collection of small planes that have been created by powerful beings, possibly The Twin Gods themselves. The planes here are constructed from delicate (or not so delicate) mixtures of other planes of existence: each plane the result of a specific recipe.

Powerful beings fold ratios of the Elemental Planes and inject an ongoing mixture of positive and negative energies. These demi-planes are routinely influenced by the beings that create them and other beings once they learn of them.

The following demi-planes are known, but it is thought there are many unknown planes that exist but are yet to be discovered.

Known Demi-Planes
Material Plane - This is the place where the physical Realm of Sesamar exists. However, it contains many worlds besides Sesamar.

Ethergreen - This is a place where elves were said to have existed before their entrance to the Material Plane (see Age of Elyon). This is a place of innocence and creatures of the forest. It is said the elves will one day all return back to this plane. This plane consists of the Positive (very little Negative), Elemental Planes, and layer from the outer plane of Asgard.

Etherdark - This place is fueled by the Negative and Elemental Earth Planes. It is a shadowy place where ghosts, wraiths, and a variety of undead creatures exist, haunt, and draw energy.

Dreamscape - This is a low energy, fragile demi-plane. Intelligent creatures often drift into these planes. mostly when they sleep. Theories exist this plane must be governed by a need to consume mental energies. It is possible this plane is actually fueled in part by the collective intelligence of creatures who exist in the demi-planes. Nevertheless, some creatures enjoy serene moments and others suffer from terrible nightmares in the Dreamscape.

Nil - This is a small plane constructed from the Negative and Elemental Earth Planes. It is possible it overlaps with Dreamscape. The creature who created this demi-plane lives here: Nihil. As a result, Nihil is extremely powerful here.