45: Chapter 45: The Ultramarines storm into Terrastar Tomb and find it littered with awakened Blackrock Engines.

Talastra's orbit was still deathly silent as Sebastian's fighter broke through the atmosphere. This planet had been marked as "Forbidden Entry" in the Imperial archives for over four thousand years. The last batch of close-range scanning data had been left by an exploration fleet from the Great Crusade era—back then, scanners had captured extremely strong blackstone signals deep within the tomb, but no one dared to excavate the surface to confirm. The Inquisition later stamped it with a "To Be Observed" mark, and after that, no other fleet ever returned.

Now Sebastian saw why no one had dared to dig. He leaped from the Thunderhawk Gunship followed by twenty Terminators. The moment their power armor hit the ground, it shattered the thin shell of volcanic ash on the surface, revealing the dark gray tomb casing beneath. With the naked eye, one could recognize the Necron architecture from the crisscrossing black patterns—true blackstone, not the imitations plated with scrap metal used by the Adeptus Mechanicus. The entrance to the tomb was a giant gate that had been buried for untold millennia, and it had already been melted through from the inside by some force. It hadn't been cut or blasted; it had been dissolved at the molecular level by blackstone resonance. The melted edges were still emitting a faint, cold green residual heat.

"It arrived before us," Sebastian said over the open channel. "The Blackstone Cerebrate is already inside. Everyone, advance at maximum speed. Don't wait for Titan support from outside—the blackstone radiation inside this tomb is too strong; the Titans' Void Shield won't hold."

The twenty Terminators entered the gate in two columns. The corridor behind the door was wider than they had expected, with walls built of blackstone on all sides, every seam flowing with cold green light patterns. Every ten meters along the walls, a Necron blackstone engine was embedded—not the dismantled remnants seen before in the Hails reliquary, but complete, functioning, primitive engine arrays that had been left to run alone in the tomb for tens of millions of years. Every engine pulsed slightly within the cold green light, and the low-frequency sound waves they emitted layered together to form a constant, unlocatable hum that pressed against the chests of everyone in the squad. Sebastian stared at the nearest engine, the tip of his Power Sword involuntarily lowering. He had seen a single blackstone engine at the Forge Temple completely suppress the psychic powers of the Grey Knights; now, in this corridor, the number of engines visible to the eye alone exceeded the sum of the entire Ultima Segmentum's Imperial reliquaries.

"Captain—these engines have all been activated," a Terminator said in a low voice. "They aren't on standby; they're running. What are they waiting for?"

Sebastian did not answer. He already knew the answer. In the largest master control room at the end of the corridor, the Blackstone Cerebrate stood in the center of the tomb. Her form was slightly smaller than a Brood Queen, and her adamantium Chitin carapace lacked exposed bone blades. Her entire cranial cavity was encased in a forehead plate covered by a network of blackstone engine node patterns, the flowing cold green light flickering in synchronization with all the engines in the tomb. The ends of her forelimbs were not scythe blades, but dozens of extremely fine blackstone probes. These probes were currently inserted into a giant Necron master control interface on the floor of the control room. With every probe inserted, a new blackstone engine deep within the tomb was awakened. The pulsing sounds of those engines bloomed one after another in this Necron tomb that had been untrodden for tens of millions of years, like an underworld fleet being awakened one by one, beginning to warm up in the darkness.

Sebastian did not hesitate. "Destroy the master control interface. All Terminators—concentrate fire." Twenty Storm Bolters opened fire simultaneously, every bolt landing precisely around the Blackstone Cerebrate, attempting to sever the blackstone probes extending from the interface. The armor-piercing bolt cores triggered a series of sympathetic detonations upon contact with the cold green light, causing the Necron script on the control room walls to flicker under the shockwaves.

After the smoke cleared, not a single probe was broken. The Blackstone Cerebrate's head slowly turned toward Sebastian. The cold green light on her forehead plate shone in the dim tomb like a silent, cold-flamed ghost star, swallowing all the light reflected in the Terminators' helmet visors into a deeper frequency of blackstone resonance.

She spoke. There was no sound, no text—it was language projected directly into the depths of everyone's consciousness: "You are three hundred thousand years late. These engines do not belong to you. Before your kind of humanity learned to use fire, they were already here, waiting to be awakened. Before your oldest Terra script was born, they were already counting every century alone in the void. Your empire calls a few dismantled engines 'holy relics'—those are but the dust fallen from this tomb. Now the key has returned. Master control interface restart complete. Talastra full array—online."

An extremely low rumble echoed from the depths of the tomb, accompanied by a shockwave that knocked the Terminators back half a step. It wasn't an explosion; it was the inert gases deposited in the Necron architecture for millions of years being squeezed out by the pressure difference as the main engine restarted. That sound was incredibly heavy and muffled, passing through the corridor, through the soil layers, through Talastra's thin atmosphere, and traveling along the blackstone network to all areas of the Ultima Segmentum still covered by blackstone engines. The Tech-Officer of the Wrath of the Emperor saw the Talastra coordinates on the scanner suddenly light up on the bridge, with a brightness exceeding the sum of all previously known blackstone signals—that ancient tomb was no longer a silent graveyard; it had become the hub of The Swarm's Blackstone Defense Line.

Sebastian roared and charged forward through the dull pain of his suppressed consciousness, his Power Sword striking three times at the base of the blackstone probes, each strike deflected by a Quantum Barrier composed of cold green light. The price was the blackstone resonance directly penetrating the psychic shields inside his armor, tearing apart all the blessings the Librarians had pre-cast while waiting outside. The Terminators tried to flank the Blackstone Cerebrate, but the tomb walls seemed to come alive—layers of blackstone gates slid out from the walls, splitting the entire squad into several isolated remnants. The Blackstone Cerebrate did not pursue; she simply read the encrypted files of the Ultramarines' Gene-seed bank row by row, recording every name and specialty into the Hive Mind.

"Retreat!" Sebastian bellowed. The remaining Terminators picked up the wounded and retreated at full speed through the corridor, the tomb's gates closing one after another behind them, leaving Sebastian alone in the control room. He reactivated his Power Sword, the blade glowing ghostly blue in the dim tomb, and then he saw the ceiling directly above the Blackstone Cerebrate's head, at the deepest part of the tomb, slowly cracking open—not shattered, not pried, but the tomb itself opening its final sealed layer to its new master. Cold green light poured out from the rift, illuminating a blackstone construct larger than a blackstone engine and deeper than a Necron Overlord's mausoleum. It was a complete Tomb-class Blackstone Gate, its surface covered in symbols older than the Necron Dynasty, symbols that even Nephilak had never deciphered.

The Blackstone Cerebrate ceased its attack on Sebastian, turned around, and inserted all her probes into the Quantum Interface of that giant gate. In the final second before his consciousness was squeezed into near-insensibility by the blackstone resonance, Sebastian saw a tiny cold-green gap open in the gate—behind the door was some undefined energy dimension, with resonance patterns purer than all the blackstone engines combined churning in the infinite distance. He did not know where that door led, but he knew one thing. What The Swarm had unearthed on Talastra was not a fortification, nor an engine array, but a door he was never meant to see opened.

A few minutes later, the Tech-Officer on the Wrath of the Emperor reported in a trembling voice: "Lord Inquisitor—the Talastra coordinates are still transmitting. That Blackstone Cerebrate is using a key to write into the base of this gate—" He dragged a section of the waveform onto the main screen, his voice freezing completely when he spoke again, "It is merging this passage into the Blackstone Defense Line, categorizing it under The Swarm's IFF codes."

Marcus Aurelian stood before the command console, not asking what that gate actually was. He simply archived all the records from the Wrath of the Emperor's scanners and sent them to Terra, with only a single line for the title: "The Ultima Segmentum Blackstone Defense Line has fallen under Swarm control. An unknown Blackstone Gate has appeared at the Talastra coordinates, target behind the gate awaiting identification. Request all Astartes still on their return journey to increase combat readiness—we are losing the borders of this sector."