Established on the fallen 'moon' known as Terra Arcana (location), the Mages Guild is one of the longest-running organisations around. They celebrate the expansion of arcane knowledge and care little for national borders, though healthy competition is welcomed between each of their branches.
The Aletheian branch was established largely in the Elven city of Ilendras, before the Aletheian Empire had reached it. They were fierce in their attacks on the former dwarven kingdoms, but stayed neutral in the Elf-Drow conflict due to their appreciation of drow arcane arts. Whilst they fought hard against the Aletheian forces as the Empire tried to take Serendel Forest, they eventually lost and surrendered to their then-rulers. As an act of good faith towards the elves to create a lasting peace, they were allowed to remain, and have since been a bastion of knowledge and education for those in the Empire.
They do have multiple schools across the entire Empire - the Everfall Mountains are a particular location of interest, especially for those seeking to learn necromancy in a safe environment away from people - both above and below ground. Whilst individual schools do hold rivalries, said rivalries are nothing in comparison to their intense competition with Thrinda's Arcanium and the Mages Guilds of other countries and continents.
Archmage - Has an immense wealth of knowledge and is charged with managing diplomatic relations with the nation. Most senior authority in the branch. Inter-guild conferences see them referred to as 'the Archmage of Aletheia'.
Spellmaster: Twelve mages fill this role and make up a council who assign roles and manage the day-to-day organisation of the guild.
High Mage of [school]: The leader of specific wizarding schools or arcane talents. They manage the curriculum for that school's teachings. Other arcane disciplines modify the title slightly - alchemists may be known as the Chief Doctor of Alchemy, bards as the Head Bard, et cetera.
Master Wizard: Highly talented mage, well-proven. For this and all other general rankings, the title changes according to discipline (Master Bard, Master Arcanist, etc). These mages often function as heads of other schools or research labs, chief mages in armies, or high-ranking advisers to members of the nobility. Generally level 15+. Master rank is required to move up in rank.
Expert Wizard: Skilled mage. Often function as researchers, professors, magical item traders or magical soldiers. Levels 11 - 15.
Adept Wizard: Middle-level of talent. Many can't progress further than here. Often researchers, low-level magical item traders, members of arcane squads and eccentrics. Levels 5 - 10.
Apprentice Wizard: Mages who know some spells and have decent talents, but have yet to prove their ability and often still need to learn more. Levels 2 - 4.
Novice Wizard: Beginners who're still learning. Levels 0 - 1, occasionally 2 depending on talents.
The Mages Guild seeks to unlock the secrets of magic and educate all who seek knowledge with a deeper understanding of the arcane arts.