For ease of explaination, Magius = Mana. Every living being (including plants!) has an aura, called "Natural Magius", which determines which element on the magius spectrum they are most attuned to. Magius can be manipulated in many ways by those trained to do it, both for the betterment of all, and unfathomable destruction.
Fire magius often manifests itself in comforting flames, such as furnace fires and the sun in the sky. People full of passion and impulse tend to find fire magius easier to wield than others, as the flames can be as unpredictable as themselves. The physical manifestation of fire magius is the Demon of Fire: Flamzar
Water magius brings life and serenity, often used as a more natural heal, as opposed to the divine intervention of light magius. Calm and open-minded is the mindset of choice for water magius users, riding the waves of fate. The physical manifestation of water magius is the Demoness of Water: Aqurine
Air magius is the most common aura found in sentient beings, representing freedom and discovery. Most practical uses for air magius is to power technological devices made in Avistra, with wind farms being their latest and greatest discovery. The physical manifestation of air magius is the Demon of Air: Airon
Earth magius is a difficult element to harness, requiring focus and steadfast determination in its users. However, in the right hands, it can do incredible things, from simply softening soil, to creating enormous fissures. The physical manifestation of earth magius is the Demon of Earth: Eathuel
Light magius isn't exactly light. Light magius is a special element in the spectrum of magius, able to cause divine acts as willed by it. This can be anywhere from healing to shielding to piercing stone in a flash, depending on its user. The physical manifestation of light magius is the Demoness of Light: Lightia
Dark magius is often misinterpreted as evil, due to its ability to bring death. Users of this element tend to be intellectual and calculating, relying on logic rather than emotion. Dark spells are infrequently cast outside of battle, often becoming clouds of deadly miasma, and flawless illusions. The physical manifestation of dark magius is the Demon of Darkness: Shadoc