Madail is a powerful Daemon of Chaos Undivided that took part in the Horus Heresy.[1a]
Long preparations were made to summon Madail from the Warp[1a], but they finally came to fruition when the Ruinstorm was cast during the Heresy and those stuck within it were unable to reliably use the Astronomicon[1b]. In the aftermath of the Ruinstorm's creation, the Xenos built Chaos structures on the Death World Pythos, acted like a beacon within the Warp Storm and this drew the remnants of the Iron Hands Legion's 111th Company and their Raven Guard and Salamanders allies to the world[1c]. Led by their Captain Durun Atticus, the Iron Hands and their allies landed upon the Death World and built a base, so that their Astropath Rhydia Erephren could study the structures in order to determine how they functioned[1d]. This was followed by the arrival of a fleet of ships[1e] filled with Chaos worshipers from Davin; who had been told by a messenger from the Warp, that they would play a key part in summoning Madail[1a]. Though the Davinites nearly met their ends at the jaws of Pythos' predators[1e], they were saved by the Iron Hands after the Company was persuaded to come to their aid, by the Salamanders Sergeant Khi'Dem and the Raven Guard Legionary Inachus Ptero. Not knowing the Davinites' true nature, the Iron Hands then allowed them to build a settlement near the Company's base, after the Davinites declared that Pythos was their new home and purposely destroyed the spaceships that brought them to the Death World.[1f]
However this proved to be the Legionaries downfall, as when the Davinites revealed their Chaos worship to the Iron Hands and their allies, it was too late to stop the ritual they had begun to enact as soon as they arrived on Pythos. When it was completed, Madail emerged upon the Death World and in the mayhem that followed, the Daemon demanded that the Davinites sacrifice themselves as blood offerings, to Pythos' predators and they willingly left the safety of their settlement. As the Legionaries in the settlement began fruitlessly attacking Madail, the Davinites were quickly fed upon by a large number of the Death World's predators and they then deliberately led the beasts to the Iron Hands' base[1a], which soon fell to the predators[1g]. As the final Davinites died, their blood enacted yet another Chaos ritual[1a], which allowed a Chaos incursion to occur on Pythos and between the rampage of the predators and Daemons, only a few Legionaries were left fighting for their lives[1g]. Knowing that their end was near[1h], and with their Strike Cruiser Veritas Ferrum having just been destroyed by a warp blast[1i], Captain Atticus led the few Legionaries near him in a charge to reach one of the Xenos structures, so that the Astropath Erephren could use it to warn Terra about Madail's presence. The Daemon sensed their intent and attacked them, but was held off long enough for Erephren to send the message, before the effort of doing so killed her. Now only Atticus remained and with the message sent, the Captain charged at Madail, but was easily killed by the powerful Daemon. Afterwards, Madail ordered the Daemons on Pythos, to use their bodies to repair the destroyed Veritas Ferrum and then used the Strike Cruiser to leave the Death World, with what remained of its Daemon flock, to attack other worlds[1h]. Though Terra eventually received Erephren's message, it was so undecipherable that no Astropath could understand what it contained and her warning went unheard.
Madail proceeded to terrorize several worlds across the galaxy under the title of The Pilgrim. The Daemon used captured vessels corrupted by the Warp such as the Veritas Ferrum to form a Chaos fleet, traveling world to world to unleash the "gifts" of the Ruinous Powers. Madail saw his mission as religious in nature, and at some point was charged with the Chaos Gods with corrupting Sanguinius, Primarch of the Blood Angels.
As Sanguinius, Roboute Guilliman, and Lion El'Jonson's fleets attempted to breach the Ruinstorm to reach Terra, they came across Madail's path of destruction and first learned of his existence. However the climax came at Davin, where Sanguinius was trapped within a portal at the altar where Horus fell. Within the portal The Angel saw a vision of the Emperor congratulating him for defeating Horus and saving the Imperium. However as the vision went on, Sanguinius realized that his father was an impostor and was tempting Sanguinius to take up the title of Emperor for himself. Sanguinius struck down his father, who was revealed to be Madail in disguise. It soon became apparent that the portal linked Davin to the Veritas Ferrum, now acting as Madail's flagship. A large-scale battle erupted across Davin's surface and space.
With trickery spent, Madail summoned his Daemonic hordes and attempted to force Sanguinius to serve the Gods. Sanguinius was trapped by Madail's servants and gave him a choice: take Horus' place as Warmaster of Chaos and serve the Gods or he would die and his sons would be forever damned by the Black Rage. Sanguinius resisted the temptations, and engaged in a vicious battle against Madail. The battle was interrupted by the intrusion of Guilliman and Lion El'Jonson as well as the Sanguinary Guard who all breached the portal to the Veritas Ferrum. In their battle, Sanguinius and Madail were badly wounded both became trapped in the portal, hanging between the Ferrum and Davin. It was then that Sanguinius' Herald appeared and took The Angel's place at the portal. Freeing Sanguinius, he charged at Madail and the two collapsed together into the portal.
Madail later reappeared leading a host of Daemons during the Siege of Terra.
- 1: The Damnation of Pythos (Novel)
- 2: Ruinstorm (Novel), Chapters 17–19
- 3: The End and the Death: Volume I (Novel) - 2:ii