Mana

Mana is the energy that allows magicians to use magic. Mana exists in all forms of life, not just magicians, although they are the only ones who use it. There is 'natural' mana that exists within the earth itself, which some magicians or magical objects, such as the grimmoires, draw their power from, in the form of "leylines". Mana is incapatible with the AIM fields that espers produce, as a result, whenever an esper performs magic he/ or she becomes severly injured.

It has been stated that as a consecuence of having trained their magical powers, Magician's Mana is so much stronger than the average person that Magician can easily tell who is a Magic user and who is not just by standing close to them.