The magic in Zos Kias is loosely based of Crowley's Chaos Magick theory.
Classifications: There are 6 different classifications of magic including Fire, Water, Earth, Wind, Light, and Dark. The last two are extremely rare.
Deities: Each classification, or element, is governed by a deity. The deities by nature set the basic rules for the magic, however they do not interefere with the human world, nor can humans generally summon them.
Guardians: Magic is used through a channel, ie, a Guardian. These are creatures that are magic-based, but can appear in any form from human to animal. They chose to create a contract with humans at their own will and leisure, and though rare, they can terminate them in the same manner. The user's powers are drawn based specifically on the guardian they make a contract with. The power of the guardian is assigned by the deities, anywhere from rank 1 (the lowest), to rank 4, also called a Council Being. The Council Beings are rumored to be able to directly draw information from the deities.