Magic

Magic is the ability to alter the universe and bend reality to one's will. It is fuelled by a mystical, invisible substance inherent to all living things, "Mana".

Usage
Mana is formed into coherent structures inside the mind, and then channeled through those structures and along the nervous system of the caster into the real world, where it behaves according to the pattern the mage cast it through.

A pattern of "Fireball" for example can be created in many ways, such as mindrunes or vocalisations, but the result is the same: a ball of flame emerges from the caster's body and flies toward a target.

Gestures and spoken spells are not necessary, but they are said to aid in aiming the spell and focusing the caster.

Soft Limits
Magic is limited by the caster's imagination, talent and mana pool. although a caster's pool can be depleted and overdrawn, this is not advisable, as it incurs a mana debt and a mana deficit, which lasts for 1 week after the debt is repaid with the caster's natural regeneration.

A circle of mages can channel their mana into a single person, who then has access to all the mana the circle posesses, but even this has limits and does not last forever.

Hard Limits
A Mage cannot affect another living creature's mana. The two current leading theories as to why are that
 * 1) Mana stops affecting reality when exposed to foreign mana, which radiates from every living thing with access to the ambient manasphere
 * 2) Mana cannot penetrate the dense layer of life energy without special conditions, like a healing spell.