Isstvan III Atrocity - Aftermath: The shockwaves of the Warmaster Horus' perfidy in the Isstvan System would be felt for millennia. Isstvan III was reborn in plague and fire, and its surface became a scarred and ruined graveyard of civilisation. The Life-Eater Virus unleashed at Horus' command and the subsequent firestorms swept the surface of Isstvan III, leaving a realm of ash and smoke scattered with the twisted carcasses of burned-out hives and dead cities. For their part, the Traitors had needed to eliminate the Loyalists swiftly, and ensure that their treachery remained a secret. Thanks to their perfidious attack, the Traitors had the initiative and a chance to use the cloak of false loyalty to prepare a decisive series of attacks against the Imperium. But the Warmaster's perfect plans were dashed by the rash actions of a brother Primarch and those within the Legions under his command who were still loyal to the Emperor.Hopelessly outnumbered and outgunned, the Loyalists held out against the overwhelming might of the Traitors and the evil of Horus. Every day the battle on Isstvan III dragged on increased the chance of discovery, and bled the Traitors of the resources they would need to strike against the Emperor. But in the end they still died, but they did so as Astartes -- Space Marines and loyal warriors of the Emperor. They had extracted a grievous blood price for the Traitors' victory and in doing so they dealt the Warmaster's newborn rebellion a grievous wound. With the blade of civil war drawn and wetted with the blood of brothers there was no turning back, and as word finally reached the Emperor, thanks to the brave actions of Battle-Captain Garro and the valiant crew of the Eisenstein, the fires of vendetta burned in the hearts of those utterly loyal to the Imperium. There could be no relenting and no forgiveness, only war!Captain Saul Tarvitz had discovered the perfidy of Horus' plans and willingly placed himself in the line of fire as he bravely flew down to the surface of the doomed planet to bring warning of the impending slaughter to his fellow Loyalists. By doing so he had managed to save two-thirds of the entire force of approximately 100,000 Loyalist Space Marines. Tarvitz, a formerly unremarkable line officer, had transformed a planned massacre into a successful guerrilla war, confounding even the great Horus' best laid plans. In this he was instrumental in the survival of the Loyalists through the virus-bomb attack and in mounting a cohesive defence against the Traitor attack, and in this perhaps also ultimately contributed directly to the outcome of the wider war. Tarvitz, along with his fellow Loyalists of the Emperor's Children Legion, apparently met their final fate on Isstvan III.Despite the traitorous actions of his Primarch, Captain Garviel Loken not only managed to survive the treacherous virus-bombing and firestorm, but he also rose swiftly to the mantle of leadership of the surviving Astartes under his command. Casting aside their former identity of the Sons of Horus, they proclaimed themselves Luna Wolves once more, and extracted a heavy toll of dead on those they had once called brother. Despite his epic confrontation with his former Mournival brothers, Loken had somehow survived his grievous wounds and witnessed the final orbital bombardment of the Choral City. Instead of viral weapons the Warmaster utilised high explosive to bring the city down and put a final, terrible exclamation mark at the end of the Battle of Isstvan III. It was a final epitaph that left no one in any doubt as to who had won.But by some twist of fate, or through the will of the Emperor, Loken did not die in the bombardment. Months later, Loken would finally manage to dig himself out of the rubble of the devastated capital. Unfortunately, Loken's mind had been broken by the trauma of the betrayal and his wounds and he had lost both his memory and his identity. Instead, he took up a new role and named himself "Cerberus" after the hound who guarded the gates of the Underworld from ancient Terran mythology, because he believed that death had rejected him. Loken was the "monster" who now haunted the burnt and broken ruins of Isstvan III for over a Terran year, killing the other survivors of the betrayal, believing himself to be the last Loyalist Space Marine in existence.Loken would eventually be found by Battle-Captain Nathaniel Garro, formerly of the Death Guard Legion and now a Loyalist Space Marine in the special service of the Emperor after his escape from Isstvan III. Garro had returned to Isstvan III with the express purpose of searching for Loken as a recruit to join the organisation that Malcador the Sigillite intended to found on the Emperor's orders that would later become the Imperial Inquisition.They encountered a handful of survivors who spoke of a beast that hunted them. Taking matters into his own hands, Garro went to the lair of the so-called beast of Isstvan III, and on discovery of the long-dead corpse of Tarik Torgaddon, he was attacked by the unkempt, nearly-psychotic "Cerberus." After a lengthy battle, during which Cerberus escaped, Garro and his companions discovered that the human "survivors" of the virus-bombing of Isstvan III were in fact Daemonhosts who had been transformed into undead Plague Zombies of Nurgle when the virus-bombing had weakened the barrier between the Immaterium and the material universe on Isstvan III, allowing the Plague Lord's influence to reign supreme. Garro and his Loyalist Astartes managed to defeat the foul creatures with the aid of Cerberus; however, once the undead had been destroyed, Garro and Cerberus once more faced one another in mortal combat. It was during this final fight that Garro managed to reach through the amnesia and fractured awareness of Cerberus to the core of the good man that remained deep within his psyche, reminding him of who he truly was, and that the Emperor still had a use for him in rooting out the corruption that was staining the Imperium. Aware of his true identity once more, Garviel Loken joined Garro and his team. With his assemblage of warriors now complete, Garro and Loken left Isstvan III for Luna to receive their first mission from Malcador the Sigillite.