"The Arcanum is the center of learning for all magical studies, and as such it determines who will or will not have access to its wealth of arcane secrets."
- — Hexen manual
The Arcanum is one of the three institutions that control human society on the world of Cronos, along with the Legion and the Church. Magic is a very powerful force in the world of Cronos, more powerful than on other worlds, and therefore it must be strictly controlled and regulated. The Arcanum is the institution that is charged with this responsible task.
The institution is led by a Arch-Mage. At the time of Hexen: Beyond Heretic, the acting Arch-Mage was the immensely powerful Menelkir, who made a pact with the Serpent Rider Korax, pledging his loyalty in exchange for the gift of Unlife.
The Arcanum is the polar opposite of the legion - it is focused on intellectual development and power. Its Magi may be physically weak, yet they wield tremendous magical powers and command some of the greatest magical artifacts in the world of Cronos, such as the Bloodscourge.