Silva Tenebris - Explorator Mission: Though penetrating the Great Rift made for an arduous journey, the Caestus Metalican arrived in the Silva Tenebris System reasonably unscathed, and made orbit without incident. Magos Faustinius swiftly ruled out dealing with the threat by simply pronouncing an Exterminatus action upon the world; research goals aside, the xenos structures were so deeply buried in the planet's crust that even starship weapons could not reliably destroy them.A full combat deployment of the fleet's assets also made little sense, given the uncertain extent of the Necrons' subterranean tomb complexes, and the existence of an unknown threat that might harm the less-augmented Skitarii. Instead the Magos Dominus moved cautiously, and sent Skitarii pathfinder units to begin mapping the planet, and a single team of Tech-priests and their servitors to examine one of the alien structures.The team found the buried structure discovred on their augers to be a labyrinthine vault made of unknown materials, badly corroded by the passage of megayears, but still intimidatingly massive and exhibiting signs of advanced, technological activity. The Explorators soon discovered two things: that the xenos that built the vaults were the machine warriors known as Necrons, meaning that Silva Tenebris was a Tomb World; and that many of the objects they found contained rich caches of blackstone, a vital strategic material for the Imperium and thew.Unfortunately, one obelisk reacted violently to the team's presence, and acted as an intruder alarm. Soon afterward, the team began encountering Necron Warriors patrolling the tomb complex. The team pressed on, destroying several Necrons, and then attempted to data-mine a relatively undamaged alien cogitator. However, they were interrupted by the awakening of a Necron individual of fearsome power: Void Admiral Agrolekh, a Destroyer Lord. The team barely managed to escape the Necron noble's assault alive, and only by fleeing while Agrolekh was busy destroying their servitor complement.Following this first encounter, energy readings revealed that the Tomb World's master control program had entered an extremely aggressive, exponentially accelerating reanimation protocol. If not stopped, within 264 solar hours it would awaken every Necron on the planet, producing a Necron army far beyond the mission's ability to contain.In the face of this threat, Magos Faustinius decided to fully deploy his entire Battle Congregation to the Tomb World's surface. The Skitarii would explore the stasis tombs chamber by chamber and maintain a foothold, and demolish every inactive Necron and war machine they found. Kill-teams of elite, heavily-augmented Tech-priests would form a mobile reserve to achieve crucial objectives and respond to crises.Faustinius' council of advisors, meanwhile, would scour the data streaming back from the deployed Mechanicus forces, identifying key objectives and threats for the special forces to take, thus making best use of the limited time available. The Magos Dominus himself made the final decisions on which missions to prioritise, as well as personally commanding the most important ones by telepresence from the command throne of the Ark Mechanicus.Though most of Magos Faustinius' advisors generally agreed on the mission's goals, and simply focused on their own areas of expertise, two exceptions stood out: Tech-Acquisitor Scaevola of Stygies VIII, and Lector-Dogmatis Videx of Metalica.Scaevola was a member of the heterodox Xenarite sect, an expert on archeotech and xenotech, charged with comprehending, navigating and appropriating any unfamiliar technology the Explorators should encounter. She proved invaluable in finding weaknesses in and paths through the bizarre technosorceries of the Tomb World, as well as finding Human archeotech. However, she also made no secret of her admiration for the Necrons' technical knowledge -- particularly high-energy physics, dimensionalism, and material science -- and her desire to add it to Humanity's own. In her mind, the Quest for Knowledge should be pursued with scant regard for even Human life, let alone obstructive dogma.Videx, by contrast, was a walking archive of Cult Mechanicus scripture and theology. His duty was to maintain the Battle Congregation's righteous courage and purity of thought; no easy task in the face of the arcane techno-blasphemy that filled every corner of the stasis crypts, and the deadliness and inventive cruelty of their inhabitants.The missions Videx recommended spread signs of the Machine God's divine favor throughout the tombs, heartening the Skitarii charged with holding them, and defeated many attempts to corrupt or demoralise the Battle Congregation. However, he believed firmly that the best counter to the Necrons' moral threat was to annihilate the source. He recommended at every turn for Necron relics to be consigned to the flames and their contents scrubbed from the expedition's data memory. Unsurprisingly, Scaevola and Videx clashed frequently.Internal Mechanicus politics aside, a fierce war soon raged beneath the bedrock of Silva Tenebris. Magos Faustinius' legions of Skitarii and cohorts of war-machines battled undying Necron warriors and Canoptek monsters throughout the planet's huge catacombs, seeking both to learn as much as possible about the mysterious and deadly automatons, and to strangle the Tomb World's immense military power in its sleep.The Adeptus Mechanicus forces were in a desperate race against time, as the Tomb World Activation protocol accelerated relentlessly. Through it all strode the Tech-priest teams, shoring up beleaguered positions, spearheading advances, discovering secrets, and turning alien machines against themselves. But so too did the Necron Lords spread their horrors wherever they appeared.Oddly, the Necrons never challenged the Caestus Metalican with voidships of their own. This may have been due to the maintenance failures and degradation of the Tomb of Agrolekh, the most likely home of Szaregon's fleet. Alternatively, the fleet may have sat idle because of the early elimination of the Void Admiral himself, who did not survive a rematch with a full Mechanicus kill-team.The Necrons were not the only threat on Silva Tenebris. At one point, an emergency protocol caused one of Caestus Metalican's quarantine decks to be suddenly ejected from the ship. Sensors detected erratic and increasingly violent energy spikes inside the ejected module, even after it crashed planetside, and these readings only ceased after a hastily scrambled Tech-priest cohort boarded the wreck. The cause of the incident is unknown, though Xenobiologis Tiresus was never seen again afterward.Darker rumors swirled as well, of blasphemously modified weapons and other hereteknica turning up in the ship's own armories, and black-robed Tech-priests treacherously cutting down their brethren with guns and blades that glowed the same eerie green as Necron weaponry. The latter can be safely discounted, however, as no one has been found who personally remembers any such event, and certainly the Caestus Metalican was not taken by Hereteks.Despite the Battle Congregation's best efforts, the tide slowly but surely began to turn against the Adeptus Mechanicus force, as the reanimation protocol brought more and more Necron war-forms online. Though the kill-teams continued to rack up crucial victories, the Skitarii battle lines were being pushed back, and already secure zones were retaken by the undying metal warriors. Just as all hope seemed lost, however, the command staff found the linchpin to everything: the Necron Overlord Szaregon's own sarcophagus.An elite Tech-priest unit was immediately dispatched, penetrating the enemy lines and homing in on Szaregon's resting place. In response, the surviving Necron Lords of the planet converged there as well, forming up their court for battle, and the Necron Overlord rose to join them personally. This was collectively the most dangerous Necron formation ever encountered by the Explorators on the planet, but by the same token, the most valuable target. By the Omnissiah's grace, the Tech-priests were victorious, bringing down the Necron Lords one by one, until finally Szaregon himself was torn apart in a storm of cleansing firepower.With the last of Silva Tenebris's Necron royalty destroyed, Skitarii all over the planet reported a sudden slackening of the assault against them, and soon the attacks ceased altogether. Clearly, the Necron Lords had been delegating a stream of orders to their constructs and fellow Necrons even while resting in their stasis sarcophagi.Without that vital coordination, the remaining Necron Warriors fell into passive patrol loops wherever they happened to be, as did the final waves of freshly-awakened Necrons. Though individually still lethally dangerous, and thronging the planet in vast enough numbers to make exterminating them a horrific slog, their controlling intelligence was gone. The surviving war-forms simply lacked the needed intelligence to win a war.