Relictors
The Relictors are a Space Marine Chapter, although when they were first founded, they were known as the Fire Claws. Then, they generally fought in the area around the Eye of Terror with the Cadian Shock Troopers. The Emperor's Tarrot showed a badly damaged Space Hulk emerging from the warp near the Forge World of Stygies in Segmentum Obscurus, the Fire Claws were mobilised to investigate. The hulk was codified as the Captor of Sin and contained a Chaos Warband led by a Tzeentchian Champion known as the Excoriator. The Fire Claws used their Strike Cruisers to cripple the hulk and then sent Terminator Assault Squads to investigate it, led by Librarian Decario and the shadowy Inquisitor De Marche. The renegades realised they were doomed and made their final stand in the vast engine room, where Decario and De Marche both fought the Excoriator.
The champion carried a Daemon Sword, forged in the heart of the Eye of Terror that had the essence of a Greater Daemon bound within it. De Marche quickly found himself out of his league as his Power Axe had no effect. His armour was cut open and had been grievously wounded. Decario's Force Sword was shattered and his Terminator Armour was cut open in one fowl swoop. Fortunatly, Decario used his Power Fist to rip the Excoriator's sword arm from its socket. Even though it was wounded, the Champion fought on, smashing down the Librarian and killing four more terminators before Decario grabbed the nearest weapon and, with a prayer to the Emperor, took off the head of the Excoriator.
Decario then noticed that the weapon he had was the Daemon Sword. Instantly he felt that this weapon could be used to defeat Chaos. De Marche warned the Librarian that only he was trained to handle such weapons. Decario handed over the weapon and they returned to their ships. Once back on their ships, De Marche explained that this weapon could be used against Chaos and should not be destroyed. With the aid of Decario, they convinced the Chapter Master of the Fire Hawks and, under the eyes of the Inquisitor, they explored the worlds around the Eye of Terror for more artifacts. Over the decades that followed they slowly collected more relics and became known as the Relictors.
Unfortunaly it didnt take long for the rest of the Imperium to discover their use of Chaos weaponry in warfare. A cell of Inquisitors, four Chapter Masters and an Emperor Class Battleship descended on the Relictors Fortress Monastery and they were forced to hand over all relics and De Marche and take on a century long penance crusade. De Marche was executed as a heretic and as part of their crusade, the entire chapter is deployed to Armageddon in the Equatorial Jungles, especially around Angron's monolith.
Sources
Armageddon Website - Details of the Third War for Armageddon Worldwide Campaign