Mage Schools

As described when discussing the Mages as an organization, the study of magic within the City-States Region is organized within a number of distinct schools. Each of these schools is responsible for managing the teaching of apprentices and for maintaining contact with full-fledged Mages that have been released from their apprenticeships. Most Mages that are a member of one of the schools will keep a correspondence with their fellow Mages, though some retreat to isolation and are rarely heard from.

Each of the schools maintains a property upon the Mage Islands, even if they do not favor single-site education. These properties - often constructed as towers or manors, depending on the school's tastes - serve to house the school's histories and documents, and offer members a home as needed no matter their station in the world. They are centers of research within each school, and even if study does not take place here the results of such are certainly stored here.
Each school's property is often maintained by young apprentices still in their early studies; where this is not the case hired servants are generally seen carrying out such duties.

This page will also detail what D&D 5E classes fit within each school. Abbreviations for those classes: XAN (Xanathar's Guide), TSH (Tasha's Cauldron), none (PHB)

The Schools of Magic

Elementalist

Favored by Mages with an affinity for the classical elements, the Elemental school teaches apprentices to manage and manipulate the raw forces of creation. Mages from this school tend towards an appearance of flashy excess, though this is sometimes simply for show - some elemental magic requires an extreme level of focus and patience.
While most members of this school will draw upon raw elemental magic, some will tap into the power that is drawn within a familiar. Such familiars can be found through communion with a simple elemental spirit, or through bargaining with a much more powerful and intelligent elemental creature. Such bargains are dangerous for the student but carry strong potential.

Evocation wizards, Wildfire druids (TSH), and Genie Warlocks (TSH) all fit within this school.

Nature

Seeking out the power that flows through the land, reveling in the feelings that come from running with wild beasts, and fighting to protect the natural order from dangerous afflictions, Mages of the Nature school are the least likely to be found on the Mage Islands. The school does maintain a grove of trees and a small library, but almost all Mages - and their apprentices - can be found far afield in nature seeking out lessons and communing with the wilds.
Nature mages will generally be found wearing green robes as a sign of their office, though they are also more than likely to not bother with their robes instead cladding themselves in leather or other naturally-camouflaging material.

Several druid subclasses fit within this school - Land, Moon, Shepherd (XAN), and Spores (TSH) - along with any clerics focusing upon the Nature domain.

Martial

Specializing in magic that assists those facing battle, the Mages of the Martial School focus their powers on protection, guidance, communication, and precision destruction. Many Mages of this school will spend time serving with the Mercenary Guild as commanders, as well as supporting parties assembled by the Militant Orders of The Order of Virtues.
Martial mages are also most likely to be drawn into service with the Sentinels - an order of Mages dedicated to hunting Sorcerers.

Abjuration wizards, War Wizards (XAN), and Bladesingers (TSH) are the primary practitioners within this school. Arcane Archer fighters (XAN) and Arcane Trickster rogues who wish to delve deeper into their magical abilities may end up here, but they are more likely to simply associate with a Mage for guidance than to formally apprentice to one.

Knowledge

This school has the greatest potential dichotomy between members - those who spend their time seeking out dusty tomes in libraries, and those who explore societies and the world to find (and share!) knowledge. Members of this school are dedicated to the finding, preservation, and dissemination of knowledge of all types. Whether seeking histories of the Imperial Era, understanding the motivations of the Guilds of the City-States, or tracking the disturbances left by a Sorcerer, the Mages of the Knowledge school are the best at ferreting out the details lost to time or hidden by subterfuge.

The Knowledge school houses members of the Bard class, Diviniation wizards, wizards with the Scribes subclass (TSH), and druids with the Stars subclass (TSH).

Spirit

Spirit mages are those who examine the boundaries between mortals and the inherently magical. They seek out an understanding of the fey, of shadows, of the magic found in dreams. Where an Elementalist mage might seek out a powerful elemental to draw power from, the Spirit mage seeks out magical beings to understand how they affect the world.

Archfey and Fathom (TSH) Warlocks fit here, as do Dreams druids (XAN) and Clerics of the Trickery and Twilight (TSH) domains

The Art

The School of The Art is made up of mages who specialize in the study of Magic as an abstract concept, or who work to further the understanding of magic through examining individual aspects of it. These mages can most often be found performing magical experiments or examining strange occurrences in the lands, seeking out the causes of magical disruption or figuring out the ways to best apply an enchantment to an object.
Mages who study magic as an Art range from creative types seeking out better tools to precise scientific types who wish to understand magic to its finest details.

This school includes Conjuration, Enchantment, Illusion, and Transmutation wizards, Artificers (TSH), and Clerics following the Forge domain (XAN)

The Dark Arts

As noted elsewhere, the Mages as an organization are not concerned with morality - only power and its responsible use. Those mages who pursue magics which might be considered unseemly or distasteful by the general public are looked upon by mages with as much respect as is due other colleagues. Members of the Watchers - Paladins dedicated to policing incursions by magical creatures - do tend to keep an eye on the practitioners of these magics, however. This is not out of distrust (or at least no paladin would admit to such) but rather because the studies undertaken by this school do tend to be rather dangerous at times.
The Sentinels tend to draw a high number of members from this school as well - wild Sorcerers can sometimes turn to such methods as they seek out power.

This school holds Necromancers, as well as Warlocks of the Old One and Hexblade (XAN) subclasses. Note that the "Old One" in this setting is yet to be defined.