(It probably would have been best to start with this but...)
In all existance, there are two types of power that make up a person's soul. They are simply called Energy and Mana. Energy is what one uses for everyday activities that involve physical action, like walking around, or punching someone (or in this world, swinging your giant battle axe...). Mana is the magical power, it allows one to form mystical power to heal or damage another. Humans are some of the few species that have not learned how to fully control their inner Mana, and therefore have evolved to have less Mana than Energy. Those humans that can control the little Mana they have are considered to have Psychic abilities, for the Mana can only be formed in a way that enhances the human's mind. Seeing as how humans have been trying to increase their intelligence for so long, it is fitting that their Mana would react in this way.
Energy is not as complicated as Mana though. It is used for physical tasks, and when it has been exausted even Mana cannot be channeled correctly, and the being is unable to move without feeling pain or is very tired. Energy can be replenished by consuming food or resting. Mana on the other hand, is very different. When exausted, it causes serious damage to the user's body. They tend to fall unconscious as well afterwards. To replenish Mana, one can rest and absorb it into their body as long as they exist in a Mana rich realm. Alchemists have also developed consumables that replenish Mana temporarily.
Mana also splits into two basic forms, the Elements of Light and Darkness. Light extends even further to the Elements of Water and Wind, and Darkness extends to Fire and Earth. Of those four extensions, they extend even further. Water extends to Ice, Wind to Lightning, Earth to Metal, and Fire to Molten Rock. When Water extends to Ice, it switches sides, and Ice is ruled by Darkness. In turn, Metal also switches to be ruled by Light. Each being with Mana has one dominant Element. Each Element is as powerful as the other, but how you use them is how you determine which is stronger. Water defeats Fire which defeats Earth which defeats Air which defeats Water. Light defeats Darkness which can also defeat Darkness.
Energy is pleantiful, and requires no source for it can naturally be regained. Mana on the other hand must come from a source, for it is mystical energy gifted to mortals by the gods and the High God (who Christians would simply call God). There are rumored to be Sources of Everlasting Mana spread throughout the world. Originally they existed in the Underworld and the Otherworld, but over time, they freely drifted from their original locations and to the Overworld. They seem to have a mind of their own, but give off Mana at a steady pace. It is also rumored that these Sources can be corrupted, and give off Negative Mana; Dark Magic Energy. This power causes most beasts to go beserk and evolve into mindless monsters that only wish to kill. It is this Dark Mana that caused monsters to develop and roam the world. But, just as the Sources are a rumor, it is also a rumor that something on the Holy Island has the power to purify a Corrupted Mana Source. Of course all of this is a rumor, but even rumors can be true.
This is the most crucial concept at the center of my world. Without these two powers, nothing could exist.
