Ethereal Plane

:It is currently unknown if an Ethereal Plane for the Dragon Homeworld or Demon Homeworld exists. Only the Third Material Plane's Ethereal Plane is currently confirmed in lore.
The Ethereal Plane is the space between the material world and the spirit world. It has the shape of the material world without living or dead matter. Existence in this plane is a combination of both borders. To imagine the ethereal plane, think of a snapshot of the material world, then remove all gasses, living mater, and dead matter. What remains is projected like a 3 dimensional, slightly out of focus, silhouette. These projections are the boundaries of the ethereal plane, and while they are immutable, their surfaces and edges are hazy to a depth of 2”. The space of the ethereal plane is a dimly illuminated misty vapor known as ether. When creatures exist in the ethereal plane, their surface manifests as condensation in the ether, but they maintain a gaseous quality. 
As the material world changes, so does the ethereal. Should a creature run into a projection, either by moving to the projection or the projection moving to the creature, the creature will typically flow harmlessly along the edge of the projection, like a gas against a solid. This makes ethereal creatures immune to attacks from the material world. There are some exceptions to this rule.
Items made from mithril, or those enchanted to exist in the ethereal plane have non-hazy projections that can affect ethereal creatures. Lead has solid, non-hazy, edges but is inert. Silver is much the same as lead, but rather than be inert is reflective.
Magical energy disrupts the ether much the same as it disrupts the material world.
:Note: The text below could be out of date with the new lore about the planes
The material plane is energy positive, the spirit plane (Felumbra / The moon) is energy negative, and the ethereal plane is energy neutral. Any bridge to the ethereal plane will create an energy flow in on direction: Material > ethereal > spirit. In the material world this usually takes the form of a cold spot, although should the bridge be mobile its movement may cause flickering flames, rustling leaves or papers, etc. Ethereal creatures projecting into the material world are sensitive to the high energies of the material plane. Sunlight is so bright as to be blinding and direct light can cause damage and searing pain to ethereal creatures.
Category:Planes
Category:Cosmology