Developed into a concrete Magical Theory by Bonisagus the Founder, the Hermetic Arts refer collectively to two magical disciplines that work together during spellcasting. There are 15 Arts divided into 5 Techniques and 10 Forms.
The Techniques govern the essential manipulations that magic can perform. Basically, they are what one does with magic.
- Creo (Cr) (I Create) is the technique that lets the Magus create from nothingness, or make something a more "perfect" examplar of its kind; this includes healing as healed bodies are "more perfect" than wounded bodies.
- Intellego (In) (I Perceive) lets the Magus perceive or understand.
- Muto (Mu) (I Transform) lets the Magus change the basic characteristics of something, giving something capabilities not naturally associated with its kind.
- Perdo (Pe) (I Destroy) lets the Magus destroy, deteriorate, make something age and other similar effects - essentially, making something a worse example of its kind.
- Rego (Re) (I Control) lets the Magus control or manipulate something without affecting its basic characteristics.
The Forms are the essentially natural phenomena that one can manipulate with magic. They represent the target of the magic or what one performs magic to or with.
- Animal (An) (animal) is used for animals. It encompasses for animals what the arts of Corpus and Mentem together covers for humans. Since bacteria were unknown in medieval times, illnesses are evil spirits, which come under Vim.
- Auram (Au) (air) is used for anything that has to do with the air, including lightning. Weather phenomena such as rain and hail may be covered by Auram or Aquam.
- Aquam (Aq) (water) is used for water, or any other liquid. This includes ice in the 5th edition; In 4th edition, Ice was Terram, since it is a solid.
- Corpus (Co) (body) is used for the human body.
- Herbam (He) (plant) is used for plants and fungi, and their products - cotton, wood, flour, etc.
- Ignem (Ig) (fire) is used for fire, and fire's basic effects of light and heat.
- Imaginem (Im) (image) deals with images, sounds, and other senses, though humans' ability to perceive them is part of Mentem.
- Mentem (Me) (mind) deals with intelligence and the mind, such as human or ghosts. The minds of animals are not affected by Mentem but by Animal.
- Terram (Te) (earth) stands for earth and minerals, or any other non-living solid.
- Vim (Vi) (power) has to do with pure magic; many spells to ban or control demons and other supernatural beings also belong to this Art, as such beings often have a form that expresses magically.
In using magic to cast a spell, you must combine one Technique and one Form together based on what kind of effect you wish to accomplish. Thus, a spell to heal a person would combine the Technique of Creo and the Form of Corpus together. Likewise, a Creo Ignem spell would create fire or the normal effects of fire, such as light or heat. Conversely, a Perdo Ignem might squelch a fire or greatly diminish the amount of light or heat in an area.
It may be possible for a spell to involve more than one Technique or Form. In this instance, the second art is referred to as a requisite. For example, creating a gust of wind and then controlling that gust of wind would be a creo auram spell with a rego requisite.
By combining these techniques and forms, the Magus may achieve any effect and spontaneously cast a spell with that desired effect, or cast a formulaic spell that they already have memorized.