Having resolved the initial crisis, I took Horus and Magnus along with the entirety of his legion and began strategizing how to neutralize the traitors. I laid out the truth of what was to come before them.
"So you're telling me that Fulgrim, Lorgar, and Alpharius are traitors... Mhm, this is troubling," Horus murmured, his heavy brow furrowing in deep thought.
"That's why you're going to call them for help to clear out a group of traitors in the Istvaan system," I explained, leaning over the strategic hololith.
"This can work," Horus conceded, "but we would need more help."
"And that we would need proof as well," Magnus added, her single eye glowing with analytical concern.
"That's why Horus is going to test them. And with this recorder, all the proof we would need is right here."
Horus bowed her head slightly. "Understood, mother."
We orchestrated the trap carefully. Fulgrim's Legion, Lorgar's Legion, and the Alpha Legion were summoned down to Istvaan III, believing they were responding to a loyalist request to take out some traitors.
Meanwhile, aboard the Vengeful Spirit, the loyalist Primarchs gathered: Perturabo, Mortarion, Corvus, Kurze, Ferrus, Angron, and Vulkan.
"What do you mean Fulgrim, Lorgar, and the Alpha Legion are traitors?!" Ferrus roared, slamming his metal fist onto the tactical table hard enough to dent the metal.
"Calm down, Ferrus. There must be a reason," Angron grunted, surprisingly playing the voice of restraint.
"There is," I said quietly, activating the console to display the recordings.
Silence fell over the room as the damning evidence played before their eyes.
"Impossible! Fulgrim wouldn't... he just won't" Ferrus muttered, staring at the holograms in disbelief.
"But it's real," I replied softly. "And we won't have a choice unless we can still save them."
Corvus stepped forward, his eyes shifting between Horus and the Crimson King. "But first... tell us about what happened to Horus and Magnus's new forms?"
"Well..." I began, exhaling slowly before explaining the situation to them.
Once the explanation was out of the way, I adjusted my gear and looked around the war room. "Well, with that out of the way... let's begin."
Down on the surface of Istvaan III, Fulgrim stood with his legion, waiting for an enemy that had yet to show themselves.
"Fulgrim," Lorgar said, stepping inside the Phoenician's grand tent.
Fulgrim glanced up. "Do you think something is wrong?" Lorgar asked, his gaze fixed on the quiet skies.
"Mhm... Not really," Fulgrim replied lightly, adjusting his armor.
"Have you seen Horus?" Lorgar pressed.
"Nope."
"No!" Lorgar gasped suddenly. His eyes widened as a terrifying jolt of warp-sensory intuition hit him. "Something is—"
Before he could finish, massive explosions tore through the perimeter.
Both Primarchs stormed out of the tent into a scene of absolute chaos. Dropping through the burning clouds, fleet-class strikes and allied ships were carpet-bombing their forward positions with deadly precision.
"Horus he betrayed us!" Lorgar snarled in disbelief.
It played out inverted from the history of another world: this time, it was the traitors caught in a lethal firing zone. Waves of drop pods screamed down from the upper atmosphere, slamming into the ground and unleashing the full fury of the loyalist legions.
"I am going to take out Fulgrim," Ferrus declared over the comms.
Landing near the epicenter of the blast zone, Ferrus charged ahead alongside his sons. I deployed directly behind him, accompanied by a heavy contingent of my Thunder Warriors and UMA Marines.
As the traitor lines broke under the overwhelming onslaught, the loyalist legions offered no quarter to those who fought on, though those who surrendered were spared and held for loyalty testing to see if any remained unsullied by the corruption.
Before long, Ferrus broke into the central plaza and confronted Fulgrim. Iron met silver as their weapons clashed with blinding speed.
Fulgrim gained the upper hand, his corrupted blade swinging in a lethal arc aimed at Ferrus's neck.
"I am sorry, but I have to intervene!" I shouted, appearing between them in a flash. I landed a heavy kick straight into Fulgrim's side, throwing him off balance.
"Agh... Mother?" Fulgrim gasped, staggering back.
"Stop this now, Fulgrim! Surrender now!" I commanded, weapon drawn.
"Never!" he screamed, his eyes burning with chaotic madness as he raised his warp-corrupted blade and charged.
I brought up an energy blade, catching his strike with a deafening energy hum. We locked weapons, trading rapid blows in a blur of motion while Ferrus engaged Fulgrim's Phoenix Guard and Lorgar's incoming forces.
"Mother, I don't want to fight you!" Fulgrim cried out, dodging a thrust from my blade and driving forward with a vicious counter-attack, which I barely managed to block.
"It must be done, son..." I said grimly.
--
Meanwhile, deep within the tides of the Warp, four dark entities watched the unfolding clash.
"This is a great opportunity!" Tzeentch cackled, weaving his threads of fate to manipulate the battlefield below.
"Now this Is getting interesting," Khorne growled approvingly.
"Yes, it is," Nurgle agreed with a wet chuckle.
"Wait—no, no, no! Fulgrim is going to kill her!!!" Slaanesh shrieked in sudden distress.
--
As Tzeentch's fate-altering magic ripple touched the battlefield, a rogue bolter round from a Word Bearer struck me squarely in the back. The force staggered me. Taking advantage of the brief distraction, Fulgrim lunged.
His corrupted blade pierced through my active shield and plunged straight into my chest the foul warp magic coursing through the edge completely bypassing my physical defenses.
Fulgrim's eyes cleared instantly. He froze, horror washing over his face. "No... What have I..." He caught my collapsing body in his arms.
"FULGRIM!!! WHAT HAVE YOU DONE?!" Ferrus roared from across the field, cutting down the last of the Phoenix Guard in a frenzy to reach us.
"It's... it's ok, Fulgrim..." I wheezed, coughing up a mouthful of blood.
"No, no, no! This can't be! I'm sorry! I'm sorry, I'm sorry!" tears streamed down Fulgrim's face as he held me, shaking uncontrollably.
"I will save you..." I forced out through grit teeth.
Using the last of my physical strength, I grabbed the length of his sword, pushed him back, and forced myself to stand.
"Sage!" I called out weakly.
Sage materialized instantly, tears falling from her eyes. With a wave of her power, she shattered the chaos-corrupted blade into harmless dust.
"Thank you..." I whispered softly.
My legs gave out, and I fell backward, caught just in time by Ferrus's massive hands.
"I can't..." I murmured, and my vision faded to black as my eyes closed.
At that exact moment, a psychic shockwave of agonizing sorrow, despair, and burning hatred echoed through every Space Marine, Thunder Warrior, and human soul in the system and across the galaxy beyond.
Aboard the Tachyon, high above the planet, Deep Sky had been commanding the fleet to dismantle the traitor ships when the wave hit her like a physical blow. A sudden, crushing weight of grief settled into her chest.
"Mother?" she whispered, turning around to see her bridge crew paralyzed, all sharing the same agonizing sensation.
A system-wide broadcast chimed through the emergency comms, Ferrus's voice breaking through the static, hollow and trembling:
"This is Ferrus Manus... Agnes Tachyon, mother... is dead."
Deep Sky's breath caught. "Mother? No... no, no, no. This is a trick!"
Her grief instantly transformed into blinding rage. She turned toward the command console, her eyes burning with vengeance as she accessed the ship's highest-clearance command protocols.
"Sisters... Mother is dead," Deep Sky broadcasted to all UMA channels, her voice dripping with ice. "I shall turn the keys of UMA."
"We will turn the keys. Mother is dead, and so are we all."
"Let mother be proud to the path we are going to walk."
Deep Sky's grip tightened on the keys. "We are going to hell. And when we do... WE'RE GOING TO DRAG THOSE BASTARDS TO DAMNATION!"
She turned the keys.
Deep within the Tachyon, sealed vaults hissed open, unleashing a dread arsenal of world-ending weapons and uncapped combat AIs. Across the field, the UMA Marines abandoned all restraint, advancing on the traitor positions with cold, merciless efficiency.
"Die!" a UMA Marine screamed, leveling a tactical nuclear launcher and firing point-blank into a traitor stronghold, obliterating everything in a blinding flash.
Overwhelmed by the loss of Agnes, some of the traitors threw down their weapons and surrendered. They were beaten down and restrained, though none were executed outright.
On that day, the sheer rage of Agnes's children cracked the very surface of Istvaan III.
--
Meanwhile, in the Warp...
"YES!!! The wicked bitch is dead!" Tzeentch cheered, throwing his hands up in triumph.
"Good for him," Nurgle and Khorne muttered, unimpressed.
"No! Why?!" Slaanesh whimpered, cringing in misery.
--
Far away, Daiwa suddenly paused, looking up toward the open sky.
"...This feeling," she murmured quietly.
Nimi stepped beside her, looking equally uneasy. "You feel it too?"
"Yes... the sadness. Did something happen?"
"Maybe..." Nimi replied, her expression filled with confusion and dread.
--
Meanwhile, on Terra...
A sudden alert flashed across an data pad inside the Imperial Palace:
[ WARNING: AGNES TACHYON LIFE SIGNS GONE ]
[ LAUNCHING REBORN PROTOCOL ]
[ LOCATING BODY... BODY FOUND. SENDING UNITS TO RETRIEVE ]
[ EVEN IN DEATH, I LIVE ]
Standing near the terminal, a Custodes looked down at a data pad that Agnes had handed him long ago.
"So this is what you meant, my Lady..." Kitten murmured quietly, gazing out at the skies of Terra.