@Tulpa: The rest of the magic system is still TBD.
Familiars... I'm going to write a tidbit about them to clarify how they work in this universe.
In the beginning the Magic users—called "the Blessed"—performed great miracles and astounding feats of power on their own. They channeled their energies alone and grew in power unguided, that is, without aid from any others but their forebears and predecessors, who had also endured such trials in perfecting their powers. A thousand years ago in the antiquity of the Blessed, a gifted youth named Ammi-Ditana walked by the riverbank. There he found a bird, whose leg was broken, lying on the brink of death in the dirt. In his mercy, Ammi-Ditana performed a mighty dead: he saved the bird and mended its wounds with his healing power. As thanks, the bird created a pact with Ammi-Ditana and became Ammi-Ditana's companion. From the bird, the youth learned to tame the wind. Because of the legend passed down the ages, Ammi-Ditana was remembered for having the first familiar, the bird who taught him to lord over the air.
Familiars serve as companions to the Blessed. The kinds of familiars available to the Blessed are these, written here in their Latin names: the animalium (singular: animalis), animals who have formed positive attachments and companionships with people; the spirituum (singular: spiritus), the spirits of people who have died and manifest in the world to serve people who call for their aid and knowledge; the geniorum (singular: genii), evil or self-serving spirits who form pacts with people to get their way; and the mortalium (singular: mortalis), people who are friends, family, or lovers of people and aid them. The Blessed do not choose their familiars, and in choosing to serve a Blessed one, a familiar does not relinquish totally its free will. Furthermore, the animalium and the mortalium can die unlike the spirituum and the geniorum, who normally lack a corporeal form and cannot be seen except by the Blessed or when intentionally revealing themselves.
The animalium function similarly to pets or tamed beasts. They usually try to protect the Blessed one they serve, and they typically follow commands easier. The Blessed can still learn more about magic with the help of animals, but animals aren't as good at teaching abilities as the spirits or the demons.
The mortalium commonly have a preexisting relationship with the Blessed one they attend to. They, the spirits, and the demons have much more free will than the animals and consequently also more intellect. Their understanding of magic is equally as limited as animals, and more often than not they learn more about magic from the Blessed than the Blessed do from the mortals. Nonetheless, they are good companions in their own regard and offer much support, especially that of the emotional sort.
The spirituum are the souls of the dead. They either leave the land of the dead to aid the living or keep their postmortem presences in the mortal world to watch over people. Their knowledge usually depends on their age. A spirit that has observed the living world for a long time knows much more than the spirit of someone who has only recently died. Unless they take the body of a recently dead animal or individual, they cannot physically aid the living, but they help by supplying knowledge and giving better advice than mortals.
The geniorum are demonic in nature. They are either corrupted spirits, that of fallen angels or of dead spirits of depraved individuals. They prowl about the world seeking mischief and evil, and their lack of morality results in their lack of concern for human life. They are the most difficult to control, and they try to form pacts in order to possess bodies and do terrible deeds or fulfill a nefarious purpose. Attaching to a Blessed one may give them more power and control, and the Blessed who join with the demons may become slaves to the demons or lose themselves and die corrupt.