In my setting there are actually two worlds.
After the overthrow of the last anti-Pope and the expulsion of the Dragoons (the old Anti-Paladin Guards of the Anti-Pope) the Roman Church moved the papacy back to Rome.
Underneath the old cemetery near Vatican Hill is a series of ancient catacombs that the Christians had made use of until Rome became Christian. Into those catacombs crept the MagnaCulta. The main "school" of magic in our world (according to my setting anyway).
There is no real magic in our world (Earth) in my setting. But on Ghantik, the other world, magic is common, though extremely dangerous. On that world is a dispute over whether magic is too dangerous to continue to use. Some want to adopt a substitute for magic, others to retain magic as it is, or even to expand the use of it.
Some dissidents who want to retain magic as it is have formed a Cabal to conduct dangerous experiments to create unique monsters (that humans call Chimera) that they hope will encourage others to use magic to combat. (Some of these creatures can only effectively be defeated or killed by magic - and if the cabal can show a need for magic to fight foreign invaders and these new monsters - which they themselves secretly created - then they think they can persuade their rulers and the populace alike to retain magic.)
To further their aims they created monsters and sent them into our world (the human world), to ravage human populations
(most people know nothing of this other world) and they have also come into out world to use their magic to loose plagues upon men and to cause earthquakes and other natural disasters. Their main target is the Byzantine Empire because the Orthodox Church and the Emperor have learned of the other world and even sent a human team to explore this other world.
This human team, the Basilegate, representing both the Church and the Empire have made allies among the local peoples (who are Elves, Giants, Dwarves, etc.) and are encouraging them to give up magic as a way of life. Many of the leaders of these people are seriously considering the idea, hence the pro-magic cabal now sees all humans as a danger.
This cabal of dangerous Warlocks and Sorcerers have sent teams into our world to recruit humans who desire to learn magic (real magic) and after training them they use these humans as their agents in our world. These Ghantikan magicians tried to establish a magical base of operations in Constantinople, but their base there was discovered and eventually destroyed.
Instead the Ghantikan magicians made contact with the remnants of the old Dragoons and the Anti-Pope in exile and using them established a secret base of operations and a magical School to teach humans who wish to become powerful Warlocks and Sorcerers. In exchange the human Warlocks and Sorcerers go back to their homelands throughout Europe and parts of North Africa and Asia Minor and establish their own secret cabals and also occasionally do work for the Ghantikan Magicians.
Both the surviving and the new Dragoons (the anti-Paladins) now sometimes act as bodyguards for the Warlocks and Sorcerers, human and non-human, though they also still dream of overthrowing the Pope, re-establishing the Anti-Pope, and killing off the surviving Paladins (now left only in France and Constantinople), Cavaliers (now only in Italy and Germany), and Rangers (scattered throughout Europe, North Africa, and Asia Minor). Some of the dragoons have now also studied magic under the Ghantikan Warlocks and have become powerful users of magic in their own right. Some have even created Chimeras from creatures native to our world.
The main base and "School" for these Warlocks and Sorcerers is in the old catacombs underneath Vatican Hill, which are now
protected from detection by enchantments. The Ghantikan Magicians, Human Sorcerers, and Warlocks among the Dragoons have taken the old Christian catacombs and turned them into an occult and dangerous training ground, laboratory for their Chimercial and magical experiments, and into a prison in which they imprison and torture humans they have captured.
They also use their Base/School as a place from which to spy upon the humans, and to "curse them" with magical disasters and plagues. There is a second such secret Base/School at Ravenna, where the anti-Pope hides in secret.
Both of these "Academies" (although the term is a loose one) are called MagnaCulta by the humans, or Jhilkãdwř (the Base) by the Ghantikan Magicians. There is the MagnaCulta Vatica, and the MagnaCulta Ravenna.
Both are extremely dangerous places, well guarded, and well concealed.
Humans are so far unaware of the existence of these places, though the Roman Church suspects that such agents are at work in the world and have formed their own specialist Team (like the Byzantine Basilegate) called the Curae, whose job it is to discover and if possible destroy such other-worldy magical cabals.