Ever-Essence

Powering the complex structures and mechanisms of the most advanced civilizations, this strange wispy substance acts as fuel, power and even currency. Impossible to hold or grasp, this strange essence requires special equipment and magics to manipulate its form. Appearing in various colours, each denoting a different unique property of the essence, many see the essence but are unable to harness it. Supposedly existing in natural abundance, there are but a rare few that have the ability to manipulate it, and but two that understand it. Two prominent individuals within their respective societies, inventors and artificers with no equal, they are the only two to ever have created anything able to make use of these essences. 
The essence itself supposedly leaks from places where the veil between planes is thinnest, the density of the substance directly proportional to the energy contained within. The colours seem to vary depending on the adjacent plane(s), with certain planes imbuing certain properties. Only existing in the Material Plane, theoretically due to the neutral nature of the Plane within the cosmological structure of the universe.
It is believed that the essences were used by the gods, back when they walked the earth, to create and power unfathomable creations and machines. Legends tell of some of these machines sitting, abandoned within ruins of divine cities. Some creation stories even mention a substance similar to that of the Ever-Essence, leading some to believe that there is a link between the energies contained within and the ability to create new life.
A new science, all to itself, the Ever-Essence holds tremendous potential. Although many questions still exist around the nature of the substance, it has already been used to create modern marvels.

Type

Metaphysical

Odor

Odorless (Typically)

Taste

Tasteless

Color

The colour varies with the adjacent plane(s).

Common State

Gas