In the Dark Arts series, the depiction of the Art of Magick is based on its descriptions in such arcane grimoires as the Book of Honorius, the Grimorium Verum, and the Clavicula Salomonis Regis.
The basic premise underlying all true magick (as opposed to staged misdirection and sleight of hand) can be described thusly:
All magick, from the simplest trick to the grandest miracle, is based on the conjuring and control of demons and/or angels. No exceptions.
A person who practices magick is an adept. The lowest order of adept is a novice. After that comes acolyte. Then the highest class, which is called karcist. A karcist who is qualified to train others is a master karcist.
Conjuring a Presence, whether Infernal or Celestial, is called an experiment. The magician conducting an experiment is called the operator. Those assisting the magician are called tanists.
A karcist gets power from signing demonic pacts. When one makes a deal with a superior spirit (i.e., a minister or governor of Hell), one earns the right to strike pacts with all of the other demons who are subordinate to it. But a karcist must choose his or her patron wisely. There are six ministers of Hell, but a karcist can have only one of them as a patron. Choose a lesser minister, and it’ll be easier to sway—but it won’t have as much to offer. Choose one of the greater spirits, and one might find oneself enslaved for eternity.
Making a demon do a task, especially one performed at a distance, is called a sending. If a karcist sends a demon to harm or abduct a person, the target is known as the patient. These antiseptic turns of phrase find their origin in Aristotelian times.
A skilled karcist can also undertake a labor known as yoking. This entails compelling a demon into service and bonding it to one’s flesh in order to wield its powers as one’s own. Sometimes such unions are limited by the terms of the karcist’s pact with each respective spirit; in some cases the demon remains bound for as long—and only as long—as the karcist remains strong enough in body and mind to hold the spirit in thrall.
Yoking a demon is miserable work. Harnessing even one can turn a karcist’s guts to mud and leave one’s head feeling as if it were used for horseshoes. Bind too many spirits, or hold them too long, and the strain can drive one mad. It is up to each karcist to decide for him- or herself where to draw that line.
Angels, unlike demons, cannot be compelled to appear or to be yoked. They can be supplicated, but if they appear, it is only because the Divine permits it. Likewise, an angel can be yoked only when the Divine grants its favor to the supplicant karcist. Yoking angels is even more painful and perilous than harnessing their Fallen kin.