Arce Secretorum

"Scientia est potentia, quia potentia ad corruptionem. Hoc ex eorum notitiam, ne forte in eo."

- The Oath of the Arce

The Arce Secretorum is a top-secret Inquisitorial facility devoted to the secure storage and study of powerful Chaos Artifacts, Daemonic Apocyrapha, and other Warp-related arcana. Created by the newborn Ordo Malleus in the years following the end of the Horus Heresy, the Arce has served the Imperium's Daemonhunters well for millennia, for the contents of it's vaults and libraries has provided many an important insight into combating the Ruinous Powers. However, those same contents are extremely dangerous, and if even a few of the relics form it's vaults were to fall into the wrong hands the results would be catastrophic, thus the existance of the Arce Secretorum is known to to a precious few.

Aftermath of the Heresy
In the wake of the Horus Heresy, the Imperium was in turmoil. The Traitor Legions had been defeated, but at the cost of the Emperor of Mankind himself, and thus great changes were made to His Imperium. During the discord of this era, the Great Scouring was underway, as the newly-formed Inquisition retook all that was lost to Chaos during Horus' civil war. During that time the Inquisition also recovered potent weapons and artifacts of Chaos that had once been used by the Traitors, and with no safe way to destroy them, the Ordo Malleus faced a dilemma. On one hand, they could not afford to keep the compiled arcana for fear of moral corruption, but on the other hand they could not risk it falling back into the hands of the Traitors. Thus a plan was formed to create a vault of sorts, a hidden safehouse in which these Daemonic relics could be safely stored, kept away from the rest of the Galaxy.

The solution was to create a space-bound fortress the likes of which had never been seen before. Using their considerable power, the whole of the Ordo Malleus requisitioned the use of an entire army of Mechanicus Tech-Priests and a Ramilies-Class Starfort, and set to work. While the outside was equipped with enough offensive capabilities to take on a small fleet, the inside of the mighty space station was reconfigured into a labyrinth of archives, libraries, and near-impenetrable vaults equipped with some of the most advanced security the Imperium could procure. The construction took nearly an entire century to complete, the Inquisition gained their finally vault in 100.M31, which they would later christen the Arce Secretorum, High Gothic for "Fortress of Secrets".