The Saviours wasted no time in executing an amphibious assault on the rebel camp where the submarine was being held, exploiting their superhuman physiology and the superior engineering of their power armour to simply walk through the rebel’s labyrinth of sea mines. Before the rebel cultists could form up to protect their gauss weapon-toting leaders, Erec devastated the rebel leadership with a terrifying eruption of psychic power, and the Saviours were swiftly able to mop up the rest of the rabble.
Incredibly, despite being burned to a crisp by Erec’s powers, Surbryte still clung doggedly to life. Under Kyme’s attentions, he was interrogated, and claimed to be a mere innocent forced to do the bidding of Chaos by the unfortunate circumstances of his birth (being a citizen of a Chaos-ruled planet). He confessed to have Inquisitor Vincent prisoner in a pit on the base, and mentioned that the Alpha Legion had indeed deployed him to forge the Reborn from a rag-tag network of minor cults into a threat to Imperial dominance on the planet. The Alpha Legion had provided supplies to run the submarine with, but so far they’d only asked him to use it to ferry groups of cultists down to the underwater city, where the cultists committed suicide by throwing themselves out of the airlock in an apparent bid to rouse the sleeping city into wakefulness. He also mentioned that the Alpha Legion hadn’t contacted him for a surprisingly long time, and that he had a teleport key for the city in his chambers, just before he expired.
The Saviours retrieved the key with ease, but extracting Vincent proved to be more difficult – he was starved, half-crazed, and seemed convinced that the Imperial Fists were actually his Alpha Legion captors come for another interrogation – and naturally, anything the Fists tried to convince him that they were the genuine article only got him more convinced it was an Alpha Legion trick. It was apparent that his mind had been broken under Alpha Legion interrogation and he had given up what he knew about the sunken city to them. After Nicolai was finally able to coax out Vincent, Inquisitor Quist was invited down to examine him and, judging that he’d a) betrayed the Imperium and b) would never again be the man he used to be, summarily executed him.
With a crew provided by the Inquisitor, the Saviours took the submarine down to the underwater city. As they approached its proximity there was an alarming moment where the submarine’s systems – and indeed all powered devices, including the Marines’ power armour – powered down momentarily, but eventually they came to the vicinity of the sunken city – at which point the teleportation stone began to glow and the party took immediate advantage of it to transfer into the city.
From within the city, they could see that the waters of the deep ocean were kept away from the city by a powerful force field, and also realised that the architecture of the city was undoubtedly Necron in origin. Luckily, the Necrons did not appear to be awake – if that had been the case, they’d have made it very, very obvious already – but one central pyramidal structure seemed to have active power going to it. Entering, the party encountered a battle where the Alpha Legion and some cultists had apparently taken on a gargantuan spider-like construct – some sort of Necron machine for the maintenance of the pyramid, evidently – and under the heaped-up corpses of the cultists the Marines found a heretical tech-priest, putting them in mind of the signs of tech-heretic activity they had discovered on Kyme’s homeworld.
Advancing into the pyramid, the party were attacked by an Alpha Legion squad, who were swiftly dealt with thanks to the potency of Erec’s Librarian powers. Deeper inside, the party found an apparent exit-teleporter – a raised circular dais, at the centre of which was a plinth with an indentation shaped to accept the teleport key. Slumped against the dais was the dying Alpha Legion leader, who – either mistaking the Fists for his colleagues or maintaining the Alpha Legion pretense of being loyalist Marines – opened up to explain to the Fists what was happening. Apparently, after removing certain devices from the tomb-city (triggering its awakening procedure), a certain “Dahzak” had betrayed the Alpha Legion before the Legionaries could put their own plan to take down Dahzak into effect.
Evidently, the mysterious Dahzak had betrayed the Alpha Legion and took the teleport key with him when he escaped the tomb-city, leaving them stranded inside – and whoever this person was, he must have been a potent psyker, for the Legion leader bore the telltale scorchmarks of a psychic attack. Slowing the awakening procedure by destroying a device which seemed to be responsible for sucking the souls out of sacrificed cultists (as well as causing the power drain that had caused the glitch on the submarine and had been sapping the Marines’ devices whilst they were inside the pyramid), the Marines headed towards the city’s power core to try and derail the awakening process. Battling their way past another of the spider-like constructs (thanks mainly to Iacomo’s heavy bolter), the Marines were able to destroy the power core and escape via the teleport circle as the city was destroyed under the incredible pressure at the bottom of the ocean trench.
After teleporting out, the Saviours found themselves back in the cult headquarters they’d found beneath the Cenotaph. Reporting their findings to the Inquisitor (as well as relaying a warning to the submarine), the Saviours heard from her that Dahzak was a name known to the Inquisition, being an infamous Chaos Sorcerer hailing from the Thousand Sons Legion, believed to have been part of the cabal led by Ahriman. The Alpha Legion had mentioned that Dahzak could be found at the world of Samech, and the Inquisitor said that she may ask for the Fists’ assistance again to tackle this apparent stronghold of the Traitor Marines.