Eon Energy (also called Sky Energy) is a type of energy most commonly known as Eon.
Although there is little known about this rare energy, Eon is thought to be composed of a mixture of Light Mana and an energy found in the seas of time and space. Such theories aren't proven, but it is known that Eon is indeed not a single energy component created. There are some accounts of Eon Energy which is indeed "invisible," like in Eon Streams.
Eon has the ability to combine with natural elements such as fire, water, thunder, etc. Although the properties of Eon are not changed, Eon seems to have the ability sort of "attract" other energetic forces and acts like a sort of glue to stick with other said energetic forces. A good example is Rye's attack, "Electreon," which is an Eon blast covered with white electric sparks.
Also, Eon Energy can still flow freely even when time stops or when the gravitational force is distorted; something commonly seen in the Sky Serpent race. Eon, besides that, is thought to allow Sky Serpents to fly in any area in which an Eon Stream is flowing. If not, the Sky Serpent's own Eon Energy can be used to fly.
Like its name suggests, Eon Energy is indeed endless.
More commonly known as Eon Jetstreams are large amounts of Eon energy flowing freely in the atmosphere of Mantua and Outer Mantua. These streams cover most of Mantua and serve as a highway for Sky Serpents.
Since Eon is a rapid moving force, these jetstreams (when crossed) take a Sky Serpent about 200MPH.
Although the origin of Eon energy is unknown, it seems that the Sky Serpent race of Mantua has the ability to conjure this energy and manipulate it quite naturally. Only Sky Serpents and their descendants have this energy within them.