Eidolon - Murder: Lord Commander Eidolon departed the 28th Expeditionary Fleet to take part in the reinforcement of the Blood Angels Legion upon the world of Urisarach, which was officially designated in Imperial records as One-Forty-Twenty, as the twentieth world to be brought into Imperial Compliance by the 140th Expeditionary Fleet. This world was discovered by that fleet, which was commanded by the Blood Angels Legion's Captain Khitas Frome.Unable to translate the warnings from the orbiting Interex satellite beacons that warned approaching starships to stay away from Urisarach since it was a prison world of the dangerous sentient xenos species known as the Megarachnids, the Blood Angels Captain Khitas Frome ordered the fleet's entire contingent of three companies of Space Marines to begin landing operations to investigate and bring the planet into Imperial Compliance.Due to the extreme atmospheric turbulence, all of the Blood Angels' shuttles attempting to land on the planet became scattered and were thrown far off-course which left the Imperial landing parties isolated from each other. The atmosphere also affected vox (radio) communications and made it difficult for the Imperial forces to coordinate their movements. Ground teams soon started sending garbled transmissions to the fleet's ships in orbit, reporting that the planet was inhabited by extremely hostile xenos.As the reports continued, the large arachnid-like xenos were described as too numerous and formidable to defeat without reinforcements. Not long afterwards, the Blood Angels made urgent distress calls requesting immediate reinforcements and extraction. The last transmission received by the fleet came from Captain Khitas Frome himself, who noted through clenched teeth, "This. World. Is. Murder." The name stuck and became the Imperium's informal appellation for Urisarach thereafter.A company of the Emperor's Children Legion under the command of Lord Commander Eidolon eventually arrived in response to the Blood Angels' distress calls. They made the same mistakes the Blood Angels had made, and had their landing parties scattered by the planet's powerful atmospheric disturbances. While the company took heavy casualties, one landing party led by Captain Saul Tarvitz discovered a large rock-like structure that resembled a dead tree. This "tree" had the bodies of several Blood Angels Space Marines impaled on its many branches with flying variants of the Megarachnids feasting upon the bodies. After destroying the structure, the sky above where the "tree" had been suddenly began to clear of the violent storms that had afflicted the Imperial forces from the beginning. Captain Tarvitz realised that these structures were actually artificial weather control devices that were responsible for Murder's heavy atmospheric turbulence.The Megarachnids immediately went about rebuilding the "tree" and sent hundreds of warriors to slaughter the last few Emperor's Children who remained. There had been little honour in the initial drop to the planet's surface, amid the death and frantic nature of the combat against the loathsomely quick Megarachnid warriors. It had been brutal, intense and bloody work, and many good warriors had met their end beneath Murder's raging, bruised skies. Thanks to Eidolon's mistakes, there had been precious little glory won until the Luna Wolves had arrived and brought their strength to bear.Just as the Emperor's Children force were about to be overwhelmed, a relief force of newly-arrived Luna Wolves Astartes from the Warmaster Horus's own 63rd Expeditionary Fleet began to land through the breach in the atmosphere. The Megarachnids were scattered and a full-scale assault on the hostile xenos of Murder began in earnest after Eiodolon butted heads with Tarik Torgaddon when the latter accused him of causing needless death for his own glory.Ten companies of Luna Wolves, the remnants of the Emperor's Children, tens of thousands of Imperial Army soldiers, and several Legio Mortis Titans proceeded to level entire swathes of the grass stalk forests and destroy every one of the "trees" they encountered, which steadily eroded Murder's atmospheric barrier. Horus, who was commanding the Imperial assault from his flagship in orbit, was very pleased with the progress being made. Some consideration had been paid to initiating a withdrawal from Murder now that a proper landing zone was available to allow an easy extraction of the troops, when an unexpected visitor suddenly arrived.The Primarch Sanguinius had come to the world to inspect the dead of his original Blood Angels landing force that had been wiped out early in the campaign. Adding five of his companies of Blood Angels to the Imperial invasion force, Sanguinius and his forces fought alongside the Warmaster against the aliens. Thousands of Megarachnids poured out of the forests and canyons of Murder in an endless wave. Despite never retreating from the Imperial assault, the Megarachnids only continued to lose ground.By the sixth solar month of the campaign it seemed the Megarachnids would soon face extinction when the fleet deployed by the Interex arrived in-system to determine who had assaulted the Megarachnids' reservation world. Finding contact with the highly-advanced Humans of the Interex to be a more pressing issue that needed to be dealt with, the Warmaster ended the campaign against the xenos of Murder.