The symbols can be modified to an unlimited degree, mostly a case of trial and error. They can be found in tomes that are publicly available, though a master runewriter will keep the details on their personal symbols private, as this makes it harder for others to modify their circles if they're not sure what it does.
Runewriting can be used for almost anything. If you're trying to do something more large-scale, like create a virus or erect a protective barrier over a location, you'd want to apply for it I imagine. Application logs could consist of acquiring the materials used for the rune and the development/theory of it. This is intentionally freeform.
A rune is an instruction, written with charged, self-reliant mana, that carries out the desires of the forger as long as there is enough mana to sustain the law. Writing of runes is considered an art among Magi, with those knowledgeable in the field especially sought after. A great runewriter will expend very little mana and design runes that are empowered by outside forces, such as absorbing mana from the air to allow the runes to consistently recharge. The letters of runes are usually blue, but Azrael's runes were known to be green whereas the runes of Kraus are a pure white. Runes cannot be altered once they're written through any means other than Divine Magic - they can only be undone.
A ritual is the gathering of mana to fuel a specific desire, usually used in conjuction with runewriting. For example, if a Magi desired an especially hard-to-crack rune spell, a ritual could be used to charge the letters. A typical to follow is to gather a team of Magi to pour their mana into the runes as they're written.
A seal is typically used to restrict power of an object unless a specific objective is met or the rune is seal is undone. It is one of the most common uses of runewriting. A skilled runewriter is needed to be able to decipher the code and, if necessary, Magi will be required to pour an equal amount of magical put into forging the seal in the first place if it is to be removed.
Organic runes can drastically alter a living creature's natural capabilities, or act as a temporary or permanent limiter to the user's abilities much like an anti-magic collar. Using runes on a living thing entails an in-depth understanding of the recipient's mana circuitry, as the runes will interact with this extensively. Examples of runes on living creatures can be seen in Azrael's reika lines upon all oscuri. It is rumoured that Kraus has his own variants, most expected on Guardians in some form.
Tampering with runes on anything organic may have disastrous results if the practitioner has little experience, tests on small animals such as rabbits, mice, and frogs have resulted in said creatures spontaneously exploding, combusting, or imploding. It is therefore one of the rarest uses of rune magic and often one of the final steps towards mastery of the art.
The more difficult the task, the more mana that's required. Runes can be charged with a number of ways, as all things physical contain mana that can be extracted to empower a ritual or a runic spell. In the summary of the resources a number is given for the amount of mana it provides, for comparison sake only.
All human examples are non-magi. A magi would multiply the output several times depending largely on their power, with up to ten times being the limit for the most powerful magi.
An angel feather was once directly linked with the angel's soul and thus it provides an enormous amount of mana. They are highly prized as most angels tend to will their feathers away after they've departed. They give at least 5000'000 mana per use, or roughly 150 human sacrifices.
The sacrifice of a human, performed in a specialized ritual to harness the body's mana, provides a great surge of energy... 3000 mana per sacrifice.
If state of the art technology is used to siphon mana from a human twenty four hours a day, leaving them heavily drained but alive, 1000 mana can be extracted per year.
Relics of AzraelEdit
Many relics will only activate when used by an Oscuri. Their power is sealed unless met with a consistent flow of rieka.
It is sealed until it senses a danger of great proportions that could threaten Valmasia itself and beyond, only materializing to a person of "pure heart" if it deems the existing populace unable to deal with the threat.
They are instructed to subdue the mana coming from the person that they're locked around. Depending on the potency of the collar, a Magi may be able to overpower and crack the rune through sheer force of will.
The Champion Sword cannot be worn by a ruler of men, nor can it be picked up by anyone other than the Champion. It will also return to a specific location if a Grand Tournament is announced.
Designed by late King of Tilandre Niklaus Eldor, these are golem based constructs driven by a combination of rune writing and earth magic. They are controlled by remote arm bands with a sequence of corresponding runes for simple commands when not directly instructed and overseen by an Earth Magi. These Constructors were used to build temporary housing for Bysonian refugees during the takeover by the Mimics, and also to remodel the Trystle Cavern entrance north of Tilandre to act as a defensive line should the outpost be taken.