Will Magic is a form of magic wherein potentia is supplied by the user's own willpower. This is in contrast to leyline magic or knowledge magic, which derive their potentia from an external stream of magic called a leyline, or from information energy.

This is the only type of magic where the user themselves is the source of the potentia. In most uses of will magic, the potentia would come out of that stored within the user's olum, but in exceptional cases the potentia could be derived directly from the user's own willpower.

Will magic could be described as the magical equivalent of an adrenaline surge, in that a user who is determined enough can temporarily exceed their usual capabilities.

Will Magic is useful in areas with poor leyline coverage, or when the user does not have the requisite knowledge or spell focus with which to utilize information energy.

Using will magic regularly, that is, draining one's stored potentia and refilling it from a leyline, will gradually improve the capacity of one's olum.

Some magic users who have repeatedly burned their willpower directly, but within the safe limit, claim that the practice has had benefits to their mental health, but this is not common and there isn't enough evidence to support that claim.

Will magic, though certainly the most flexible source of magic, can also be the most dangerous to the user. If a user's olum is empty of potentia, then the spell cast using will magic will instead consume that user's willpower itself, damaging the olum (potentially significantly) in the process, causing a condition known as olum inversion. While this can sometimes be the only way out of a situation, the result of burning one's willpower is that the user may suffer permanent psychological or physiological damage in the aftermath.

In mild cases, after burning a small amount of willpower, a user may experience some temporary doubt or aimlessness. But in progressively more advanced cases where more willpower is consumed, the user would experience lethargy, exhaustion, self-hatred, or depression. In extreme cases, bodily functions are affected, resulting in much lower metabolism, reduced cardiovascular stability (arrhythmia is a known side-effect), physical atrophy of the brain (similar to dementia), and reduced immune function. In particularly advanced cases, the symptoms may progress to the point of total organ failure.

While in mild cases, injuries from willpower burning may be reversed and to an extent fully healed, in extreme cases, they cannot be healed at all.

It may be helpful to imagine one's body as a waterskin. In mild cases, the waterskin is drunk and is then empty. This would result in the waterskin taking on a deflated and withered appearance. However, the solution is simple, merely refilling the waterskin (analogous to a potentia transfusion from a healthy person's olum to the afflicted person's) will fix the issue.

But in more extreme cases, the waterskin itself is torn or ripped. Refilling the waterskin with water will no longer fix the issue. Because the Olum is not physically located in the body, it cannot be repaired surgically. Damage to the olum from willpower burn is considered permanent and irreparable.