Summary
Slumbering entity beneath the Noctis Labyrinthus, identified in Mechanicus legend with the C’tan Mag’ladroth and, by some Tech-Priests, with the Machine God itself.
Lore
The Dragon of Mars is the cryptonym Mechanicum legend gives to a vast, sleeping entity sealed beneath the Noctis Labyrinthus of Mars — Forge Primus. The dominant interpretation across modern canon equates it with Mag’ladroth, the Void Dragon — one of the C’tan, the star-gods worshipped by the ancient Necrontyr, and held by some to be the greatest and most terrible of their kind, a master of the material realm.
Its presence is the buried heart of the Red Planet’s mythology. The contamination warnings that ring the tunnels are, in the deepest tradition, a fabrication maintained by the ruling Magi to keep curious Tech-Priests from descending toward the prison.
Imprisonment
Canon holds that the entity was defeated and imprisoned within Mars by the Emperor of Mankind long before the founding of the Imperium — in the Age of Strife or earlier. The seal is maintained, and the Dragon dreams. Its dreams, in one Heresy-era reading, were the seed by which the Emperor orchestrated the rise of the priests of Mars and the first machines of the Cult.
Connection to the Omnissiah
A current of Mechanicus theology — heretical to some, doctrinal to others — holds that the C’tan Shard of the Void Dragon, or the Dragon itself, is the actual Machine God the Adeptus Mechanicus venerates as the Omnissiah. Under this reading, the Cult’s worship has been pointed, knowingly or unknowingly, at a sleeping star-god beneath their own forges.
In the Heresy
The Dragon’s prison is the secret pivot of Graham McNeill’s Black Library novel Mechanicum (Horus Heresy IX, 2008). As the Schism of Mars (Heresy of Kelbor-Hal) erupts, the latent psyker Dalia pursues visions of the Dragon into the Noctis Labyrinthus and reaches its lair, ultimately taking on the role of Guardian as the rest of Mars falls to the Dark Mechanicum.
Shard and Aftermath
In the 41st Millennium the Necrons field a C’tan Shard of the Void Dragon — a fragment of Mag’ladroth’s shattered, enslaved essence, the most technologically advanced of its kind, able to harness raw noctilith. Even a faint shadow of the true Dragon’s power, a loose Shard once gorged itself on a dozen Necron worlds of the Arotepk Dynasty in 912.M41.