In M41, Madox led a small force to a secret hideout on the Wolves' home planet of Fenris itself, beneath a mountain called the Daemonspire. He had opened a gateway to the Warp and was preparing to launch an invasion of the Fang. He was confronted beneath the Daemonspire by a small pack of Blood Claws, including Ragnar and Strybjorn Grimskull, who together managed to banish him to the Warp[1a][1b].
Madox somehow managed to return from the Warp, and traveled to the planet of Garm, through a warp rift opened by a follower of Tzeentch. Madox manifested before Ragnar by consuming the physical form of a cultist, and fought alongside the Thousand Sons to turn Garm into a Daemon World and the new Prospero. Managing to steal the Spear of Russ from its holy shrine on Garm, Madox planned to use it in a ritual to summon Magnus the Red, the Thousand Sons' Daemon Primarch, from the Warp, for the purpose of raising the fallen Thousand Sons who had died over the millennia. The ritual failed when Ragnar cast the Spear into the rift through which Magnus was to come, closing the rift and saving the planet. Madox disappeared in the chaos of the battle2.
However, Madox managed to return from the Warp again, and orchestrated a new plot to summon Magnus and destroy the Wolves. Retrieving the Spear of Russ from wherever it had gone, he suborned Commander Cadmus, a Fallen Dark Angel masquerading as an Imperial commander, to lure the Space Wolves and the Dark Angels to Hyades and trick them into battling each other. In the chaos, Madox's agents stole a large volume of geneseed from fallen Space Marines, which was a necessary ingredient in their ritual3.
With the Spear, and the geneseed, the Thousand Sons launched the final stage of their plot, with a massive invasion against several worlds under the Wolves' protection.
The plot was centered on the planet Charys - or, to be precise, a "shadow copy" of that world that they had managed to create within the Warp. Traveling back and forth between that world and the real Charys, Madox lured Wolf Lord Berek Thunderfist into an ambush and critically wounded him, dealing a severe blow to the strength and morale of the defending Imperium forces. Under the relentless attacks of the Chaos forces, the Imperial commanders became increasingly desperate, and started a countdown towards Exterminatus of the planet.
Just when events were at their lowest ebb, a strike team, lead by Ragnar, made its way to Madox's shrine on the shadow-Charys. Hopelessly outnumbered, the Space Wolves were nearly overwhelmed, but Haegr the Mountain managed to close with Madox and retrieve the Spear, though Madox mortally wounded him. Without the Spear, the ritual failed, just as Berek Thunderfist regained consciousness and rallied the surviving Imperial forces. Ragnar himself killed Madox by driving the Spear of Russ through the faceplate of his armor4.
Years later, when Ragnar was suppressing a Chaos-fueled rebellion on an unnamed planet, he heard rumors that Chaos Space Marines were among the enemy forces, and that Madox was leading them[1c]. Ragnar was not sure whether this was true, but given the way Madox was able to manifest himself on Garm, through the body of a cultist, it is possible that he can never truly die, and eventually returned to the material plane.
- 1: Space Wolf (Novel) - The Space Wolf Omnibus by William King
- 2: Grey Hunter (Novel) by William King
- 3: Sons of Fenris (Novel) by Lee Lightner
- 4: Wolf's Honour (Novel) by Lee Lightner