Magic

Magic in Zammintar is a based on several schools of magic. Study into those schools and their subsequent disciplines allow a person greater access and capability with the spells in that school. In order to wield those spells, a practitioner must have studied at least some of that school of magic. Doing so will offer them an amount of understanding that can effect their proficiency with spells within that school. One who does not also study a discipline within the school can not simply preform those spells however. For example, studying some fire Evocation grants the practitioner the ability to use any of the spells within the discipline, even if they won't be very good with them without increasing their knowledge and or proficiency in said discipline.   The spells within a discipline may or may not be the only method to achieve what they do. There is often times when there is overlap between different schools that can allow some one to accomplish nearly the same thing, only via a different method. For instance, an Evoker can create and manipulate fire, but a Conjurer could conjure fire into existence from from somewhere else, a Transmuter could change some of the air into fire (even though it won't burn very long) , and so on. So while there is overlap, usually, an effect is easier to achieve in a different school. In the aforementioned fire example, while the Conjurer and Transmuter can both set things on fire via different means, only the Evoker can actually control the fire.
Casting or manipulating magic involves the Aura in One manner or another, as does resisting its effects. For example an Enchanter who imbues things with magic also imbues those things with some of their own Aura in some fashion, whether that be placing Aura within and tying an insignificant thread of Aura to oneself or carving it from their own Aura to create something more permanent. This is not to say that those objects necesarily have some sort of sentience but the permanent removal of part of your own Aura is enough to frighten most from that prospect.