It had not been Guardsman Yarmoth's day, or even week. The unfortunate soldier had woken up to mud soaking his boots, before being reassigned to go attend the Basilisk vanguard. The Guard had been shelling the position of the Chaos heretics for much of the past month, but in truth there was a mere scratch upon decades of shelling that had reduced their myriad warren of tunnels and strong points to little more than a smoking craters and rubble.

But still, the Chaos filth persisted and took hold like a weed, or so their Commissar had told them, and as a result they were needed to push for a new strike. The heretics had become emboldened, apparently receiving a trio of Thunderhawks the previous fortnight. Yarmoth had heard from some of the Ratlings at the dining bunker that the Thunderhawks had deposited some Chaos Space Marines, a comment that sent chills up Yarmoth's spine.

However, he felt somewhat more secure when he caught sight of the enormous cannons, the thunder audible for miles away, and rattling his very chest from this close. Even a Space Marine, as terrifyingly mighty as they could be, was little match for a shell the same size of them, landed with unerring precision on their position. So it was with some surprise that he was forewarned of his fate by only the unnervingly close rev of the saw blade, before his skull was split in half by the grinding teeth of the chain axe Gorecleaver.

Khârne the Betrayer laughed, a noise not filled with mirth but merely unhinged satisfaction, as yet another spray of blood stained the countless layers darkening his armor. He was among the crews of the Basilisks like a hurricane, cleaving men and steel and flak armor like it was little more than cumbersome paper. Yarmoth's body had barely begun to cool by the time Khârne had finished obliterating the remainder of the Basilisk detachment. Three dozen artillery pieces devastated and over a hundred men dead in the span of just a few minutes, and not even enough of bloodbath to warrant a footnote in his own personal history.

It was as he stood atop the smoking husk of the final Basilisk that the Betrayer caught sight of a Rhino barreling towards him. He laughed again, gunning the motor on his chain axe as he watched and readied himself for another charge into battle.

To his disappointment though, the Rhino stopped several hundred yards away. There was no large weaponry installed on it, and even the front bolter was angled downwards, unmanned. A quick triggering of the thermal sensors in his helmet revealed only a single occupant, a mere human unclad in anything more than the robes of the sniveling Inquisition. However, the insignia on the front of the rhino was not one that he recognized. It was a trio of gilded arrows pointing inwards, but confusion rapidly gave way to anticipation as he obligingly charged his plasma pistol and leveled it at the target that had been provided. He saw the lone human pop the hatch of the rhino, bracing something against their shoulder as they prepared to fire it.

Khârne growled in response, ready for some painful hellish fury to be unleashed. But instead, there was just a quiet thunk and something was lobbed out of what appeared to be a converted grenade launcher. The cargo landed a few paces from him, before cracking in half with a hiss and puff of harmless smoke. Within was some sort of printout, a picture of an unoccupied mountainside, but little else. He cocked his helmet in confusion, the threat having apparently been harmless, but looked up as he heard the distant vox squawk of the Rhino driver saying "Cargo delivered, my lords."

The Betrayer snorted, and in a span of heartbeats closed the distance to the Rhino, rending it and the feeble human inside into little more than metal scraps and bleeding offal within moments. Still, for the first time in more millennia than he could count, the betrayer shivered with unease.

Dozens of light years distant, there was a series of loud rumbling thumps from deep within the Imperium Anomalies fortress-bunker, as hundreds of bulkheads and redundant defenses for breached by the passage of something unstoppable. The tunnels and passageways had been mostly abandoned, but they were the occasional shrieks of pain and splintering wet sounds of brutal death as the entity passing through encountered more prey to destroy.

Finally the destruction reached the surface of the dusty moon, and after pacing in a worried circle for almost an hour, the entity began digging straight down. It proceeded to do so for another hour, making almost a full kilometer of distance in a ragged hole, unimpeded by dirt, rock, concrete, or steel. Having apparently reached the necessary depth, it turned, and with a final howl sprinted faster than the eye could see and launched itself out of the hole and into the stratosphere, quickly disappearing into the cloud layers and beyond. From a secure observation room below, the Lord Scientist Bright keyed his vox recorder:

"Well, I suppose this is a new behavior we can add to this SCP's capability. Now all we have to do is wait."

314 years later:

Air Caste pilot Kor'la Kit'Au choked a curse into her helmet as she urged her Manta to bank, the Chaos Heldrake that had been soaring directly at her passing under a wing and leaving a scraping trail already starting to sputter and catch fire. A dozen auto turrets and drones pivoted and began raining fire on the offending craft, quickly reducing it to a ball of plasmic flame that immediately cratered towards the distant surface below.

She had registered the damage diagnostics and just begun the nanotech repair protocols, when her stellar positioning sensors warned her of an incoming projectile from far above. It was traveling too slowly to be a spacecraft, but too quickly to be a mere high altitude bird or other native fauna. As she keyed in the camera clusters to focus in on whatever this might be, all she can make out was a distant, roughly humanoid shape, limbs uncomfortably long and covered with matted hair. It opened its mouth as she saw it, and even though she could not hear the howl she could tell it was screaming at a volume that would have ruptured her eardrums had she been close enough.