Spirit represents a Caster's Ability to bend the void to the will of the Caster.

A a void bender gains power from practice or becoming more in tune with his/her emotions and Spirit they can cast more powerful Spells or bend the void to their will as they master themselves.

This power is innate to the Caster. The Caster can often feel their power increasing as their Body syncs with bending, and the void.

Some benders plateau, as the stress from bending is too great for their Body, Mind, emotion, existence, and Soul to bend further, more powerful Magic.

It is a numerical value that is the sum of the total Caster level, that is summed from all Caster classes.

Full Casters have Spirit equal to their Full Caster(s) Class(es) Level(s). Half Caster classes take half their level rounded up to calculate their Spirit.

For monsters and other creatures, Spirit is equal to their Challange Rating.

Spirit determines how much Mana a creature can have. The creature then spends Mana based on the Spell level. A first level Spell costs 1 Mana, and 2nd level Spell cost 2 Mana, and so forth. Once the creature's Mana reaches zero, it cannot cast anymore Spells except for Cantrips.