In the Imperium perhaps the most important pillar of the Emperor’s power is the Arcane Directorium that oversees the application of magic within the empire. They provide training and employment for most arcane magic users.
Their academies attract student from all corners of the continent, not only because of their high standards in education but also because Directorium members are given preference in the empire (and high-level jobs are exclusive to their graduates).
The most infamous branch of the Directorium are the inquisitors: masters of mind reading, who weed out disloyal elements both in the military and the government. Common folk in the Imperium are often deferential to Directorium wizards as they fear the visitors might be inquistors.
The Directorium is also the source of the Imperium’s most powerful weapons, the magical Edicts. It is unclear how these powerful spells are made, only the very top of the Directorium leadership knows. What is clear, however, is that to make an Edict the Directorium mobilizes hundreds of its members to channel their power into these scrolls.
Nominally, the Directorium has no leader, it is governed by a council of archmages. In reality, they are always vying for power and plotting against each other, the level of intrigue and infighting among archmages is legendary. Both Marius II and the late Gregor I chose Archmage Travenus to be their personal advisor, making Travenus the most influential archmage and thus the de facto leader of the Directorium.