Vakrah Jal - Cull of the Word Bearers: As the Horus Heresy unfolded, Lorgar ordered his subordinates Erebus and Kor Phaeron to strike a vital blow against their most hated rivals, the XIIIth Legion, the Ultramarines. Unknown to Erebus or Kor Phaeron, their primarch had a secret objective in mind when he had sent his two most zealous sons to launch a surprise assault on the Ultramarines' world of Calth.Lorgar's most trusted servants were more than willing to gain the chance for vengeance upon the Word Bearers' hated foes, pinning the enemy forces down in the Realm of Ultramar while the main forces of the Traitor Legions advanced on Terra under the command of Horus.After their humiliation at Khur, thousands of Word Bearers within the XVIIth Legion detested the Ultramarines. Lorgar ordered a great gathering of his Legion while their fleet was already en route to Calth.The primarch called for Argel Tal, the leader of the Gal Vorbak, and one other Word Bearer officer. These two loyal sons would eventually become commanders and apostles amongst the elite of the Vakrah Jal. The primarch wanted their counsel on what to do with those amongst their Legion he no longer trusted.The Word Bearers had culled their ranks down through the solar decades, removing such unrepentantly Loyalist elements as the Terran-born warriors of their Legion, but had carried out no purge like the Isstvan III Atrocity that the World Eaters' Primarch Angron was so proud of. Lorgar knew that the loyalty of his own Legion to both him and his vision of Mankind transformed through an embrace of Chaos was never in doubt, but competence was another matter entirely.Lorgar asked what should be done with those warriors of the XVIIth Legion he felt were no longer reliable; those whose hatred burned brighter than their sense. For tens of thousands of them -- whole companies, whole chapters -- their rage was no longer pure.It was decided that these suspect elements of the XVIIth Legion would be gathered into a single host and ordered to undertake the "sacred" mission to Calth to assault the Ultramarines that they had so craved.They were led by Erebus and Kor Phaeron and were expected to martyr themselves in glory. The other Traitor Legions such as the Emperor's Children, Sons of Horus and the World Eaters might have purged their own ranks at Isstvan III, but the Word Bearers proceeded to purge their own during the Battle of Calth.Though the XVIIth Legion achieved a monumental victory of sorts at Calth, it was all a matter of perspective. Piercing the veil of the Warp, Lorgar had heard the whisperings of the Chaos Gods and had witnessed the truth for himself.As expected, Erebus had successfully conjured the great Warp Storm known as the Ruinstorm at Calth which would help prevent the Ultramarines from reinforcing the other Loyalists on Terra as Horus' forces closed on the Throneworld.But ultimately, Erebus and Kor Phaeron had failed to achieve their overall objectives: Roboute Guilliman was still alive, the Word Bearers had lost half their fleet at Calth to an Ultramarines counter-attack, and tens of thousands of Word Bearers, including the Gal Vorbak and the mortal servants amongst their countless allied Chaos Cults, had been abandoned to a useless subterranean Underworld War beneath Calth's irradiated surface while the two Word Bearer commanders had fled.Though Lorgar was somewhat displeased, Erebus had more or less achieved the base level of success required of him; the Ruinstorm had been conjured and the rogue elements of the Word Bearers had been culled.