Meanwhile, deep within the Warp...
"Wait... I can still salvage this!" Tzeentch muttered, his shifting forms coalescing into a manic grin.
He gestured to a lurking demon. "You! Demon! Give Magnus a vision about his mother going to destroy the Imperium!"
"And have some of my power make him kill her!" Tzeentch added, practically cackling.
"Yes, my lord," the demon hissed before vanishing into the swirling immaterium.
"Who wants to bet that Tzeentch fails this one?" Khorne grunted, leaning back on his throne of skulls.
"Me!" Nurgle raised a bloated hand.
"Me too!" Slaanesh chimed in with a smirk.
--
After arriving in the Prospero system, the dropship prepped for descent.
"Mother... how do I even meet Magnus when I look like this?" Horus asked, glancing at her current Endmin appearance.
"Don't worry, I have this!" Agnes said, pulling out a disguise kit with a flare. "With this, you can fool Magnus! Though, to be fair, it's only a 30% chance it'll work... but hey, a chance is a chance!"
Agnes handed the kit over to Horus.
"Agh..." Horus let out a heavy, tired sigh.
"Don't be like that, Horus," Agnes nudged her affectionately. "So then, let's get going!"
Before Horus could protest any further, Agnes pulled her toward the Thunderhawk.
The transport breached the atmosphere and settled onto the landing pad.
"Alright, Prospero. Yep, full of churches and stuff," Agnes remarked, stepping down the ramp.
Flanking her were Deep Sky, Admire Aura, and Little Amapola. Horus followed behind, escorted by Abaddon and two of his Honour Guards.
"Alright, remember your lines and we will survive," Agnes whispered, giving a quick wink.
As they cleared the ship, they were greeted by Ahriman and Magnus the Red.
"Mother! Welcome to Prospero," Magnus said, stepping forward with open arms.
"Well, it surely is something," Agnes replied, offering a warm smile.
"Follow me to the palace, Mother," he offered.
They followed him up the grand steps, but as they walked, the atmosphere grew increasingly tense. The hair on the back of Agnes's neck stood up as dozens of Thousand Sons warriors began silently falling in behind and beside them.
"He is denying Father's ban," Horus whispered under her breath.
"It looks that way," Agnes whispered back, her eyes darting to the converging Space Marines.
Finally, they reached the main courtyard of the palace. Magnus suddenly halted, spinning around as his crimson skin flushed with anger.
"You think you can fool me!" Magnus bellowed.
In a fraction of a second, his sons raised their weapons, locking their sights directly onto Horus.
"What is the meaning of this, Magnus?!" Horus demanded, stepping forward.
"You're not Horus! Nor mother!" Magnus roared.
Psychic energy flared around his eye, a blinding wave washing over Horus that instantly shattered the disguise kit's illusion.
"Mother, no! You're surrounded by imposters wearing their faces!" Magnus yelled.
"Magnus?" Agnes started, taking a step forward.
Before she could finish, Magnus unleashed a massive psychic blast directly at her. Agnes reacted instinctively, teleporting out of the strike zone just as the energy obliterated the ground where she had been standing.
"Magnus! You traitor!" Horus screamed.
She raised her comms, calling in her legion. The sky darkened almost instantly as dozens of Sons of Horus drop pods tore through the atmosphere, slamming into the plazas surrounding the palace.
"Horus, no!" Agnes cried out.
Ahriman whipped his staff around, throwing a arc of psychic lightning toward Agnes, but her personal energy shield flared to life, absorbing the strike completely.
"Call our sisters! Protect Mother!" Deep Sky shouted into her radio.
High above, even more drop pods began to rain from the clouds.
"Deep Sky! Don't!" Agnes yelled, but her voice was completely drowned out by the chaos of battle.
Agnes grit her teeth, her gaze locking onto the giant Primarch. "You..."
She charged headlong at Magnus. 'I need to stop this before more people die!' she thought urgently, calling upon the power of the Chaos Emeralds hovering around her. 'I can't beat Magnus without weakening his psyker powers, but with this, I can win!'
A blinding flash of golden energy erupted around her as she transformed into Super Agnes.
"It's... it's the Emperor's light!" one of the Thousand Sons gasped, lowering his weapon in awe.
Super Agnes rocketed toward Magnus. Several Thousand Sons stepped into her path to shield their Primarch, but their weapons couldn't even scratch her glowing aura.
"Magnus!!!" Agnes screamed, flying straight through their line and delivering a devastating punch across his jaw that sent him tumbling backward.
"What!?" Magnus gasped.
Before he could recover, Agnes vanished, reappearing behind him to drive a brutal kick into his spine, sending him face-first into the stone floor before blasting him with a concentrated burst of energy.
Die deamon!" Magnus growled, pushing himself up and firing a massive, concentrated beam of warp energy.
The blast hit Agnes head-on, knocking her back across the courtyard.
"Ahahaha!" Agnes let out a sudden laugh as familiar dark whispers flooded her mind.
"That's it! Punish him!"
"Don't stop now! Destroy him!"
The voices surged, trying to push her over the edge, but she gritted her teeth and slammed her fist against her temple.
"If you want a piece of me, then fight me!" she yelled aloud, trying to expel the dark thoughts. Slowly, the voices began to quiet down, receding back into the dark corners of her mind.
momentarily stunned as he watched her struggle against herself.
Realizing her distraction, he gathered his power and unleashed a heavy psychic blast. The attack slammed straight into Agnes, launching her across the plaza until she cracked into a stone wall.
"My sons! Kill all of these imposters!" Magnus bellowed, turning toward his alter to begin a ritual. "I will contact the Emperor myself to report these fiends and request reinforcements!"
"Magnus, you're an idiot!" Agnes screamed, bursting from the rubble.
Caught completely off-guard, Magnus was sent flying across the courtyard as Agnes tackled him mid-spell.
"Aghhhh!!!" Magnus roared, unleashing the raw, unfiltered power of the Warp to blast her away into the sky.
"Chaos Control!" Agnes called out, freezing her momentum and instantly teleporting behind the falling Primarch. She grabbed him by the waist and brought him down into a crushing suplex onto the hard marble.
"Listen to me, Magnus! I am not an imposter, nor was Horus—"
Magnus refused to listen, his eye glowing with mad desperation as he fired another point-blank psychic blast that knocked her back once more.
"Tsk... Metal Sonic, help me out!" Agnes yelled, summoning the mechanized hedgehog in a flash of light. "Metal, beat him up! But don't kill him!"
Metal Sonic's eyes flared red as he rocketed forward, engaging Magnus instantly. He landed a lightning-fast kick straight across the Primarch's face, driving him back just in time for Agnes to close the distance and plant a heavy punch into his stomach.
"I HAVE HAD ENOUGH!!!" Agnes screamed.
"CHRONO CONTROL!"
Time ground to a complete halt. The falling dust suspended in mid-air, the roaring Space Marines frozen in place, and Magnus stayed locked mid-stagger.
Working fast, Agnes quickly deployed multiple devices around Magnus that emitted a heavy field of Blank energy, completely nullifying the Warp around him, before building a reinforced containment box around his frame.
"Time shall continue," Agnes commanded.
The world snapped back into motion, and the effects on Magnus were instantaneous. Cut off from the Warp, he collapsed inside the box, gasping for air.
"Let me out!" he demanded, banging his fists against the walls.
"No. I am Agnes. The real one," she said firmly.
"Liar!"
"Then this shall convince you," Agnes said softly, pulling out a handful of photographs and holding them up to the viewport. They were pictures the two of them had taken together on Terra, smiling and laughing.
Magnus stared at the photos, his single eye widening as realization shattered his panic. "No... this can't be. The visions... they were wrong!"
He looked up at her, his face crushed with overwhelming sorrow. "I... I am sorry..." he murmured, hanging his head low.
"It's not over yet. Tell your sons to surrender no more blood shall be spilled today," Agnes ordered. She turned to her mechanical ally. "Metal, carry him outside."
When they stepped out of the palace containment zone, a full-scale war was raging across the plazas of Prospero.
"Do it," Agnes said, looking at Magnus.
"Yes, Mother," he whispered. Gathering what little psychic strength he had left, he projected his voice across the entire city.
"Surrender, my sons! Lay down your arms!"
Agnes raised her hand to the sky and fired a glowing beacon, signaling all of her legions to cease fire. Pulling out her communicator, she opened a channel to her daughter.
"Horus, tell your sons to stop fighting. I have Magnus," Agnes said.
"Yes, Mother," Horus replied over the static, immediately issuing the stand-down order.
Within the hour, the fighting had completely ceased. The Thousand Sons and Magnus were stripped of their weapons and secured under heavy guard. However, as Agnes scanned the ranks, she noticed something was terribly wrong.
"Mother, we are still missing multiple Thousand Sons," a Space Marine reported, running up to Agnes with a datapad.
"Who?" Agnes asked, taking the list. Her eyes widened. "...Horus! Find them! Find Ahriman!" Agnes ordered with burning urgency.
But it was already too late.
Across the courtyards, several Thousand Sons marines began to stiffen. Their power armor groaned as faint, glowing dust began to leak from their joints.
"My sons... no!" Magnus cried out.
"Brother... I don't feel so good..." a Thousand Sons marine muttered, reaching out to his comrade before his entire body collapsed inward, leaving behind nothing but a pile of empty, ash-filled armor. The Rubric had begun.
"Magnus, I have an idea to stop this... but..." Agnes hesitated, looking at him carefully.
"No matter what it is, I will take it to save my sons!" he pleaded without hesitation.
"Then... take this," Agnes said, pulling a glowing vial from her coat. "Drink this. Your sons will be saved, but you and them will be forever changed. Their flaws will be gone, but there will be... side effects."
Without a second thought, Magnus popped the stopper and downed the entire vial.
"Agh!" Magnus gasped, clutching his throat as his body erupted in a violent flash of light.
The physical changes were immediate and drastic. His massive frame shifted, his sharp features smoothing out.
After a long moment, the light faded. The figure opened her eyes.
"Mother?" she asked, her voice now light, soft, and distinctly feminine.
Agnes blinked, staring at the small, white-haired figure standing where the giant Primarch used to be. "...So, congratulations. You're a 'her' now."
"What?! Give me a mirror!" Magnus demanded.
Agnes handed her a shiny piece of metal. Magnus stared in complete shock at her reflection.
'Cute. Magnus turned into Frieren... weird, but somehow it fits,' Agnes thought to herself.
Suddenly, gasps echoed across the plaza as the same magic swept through the remaining Thousand Sons, stopping the dust spell in its tracks and altering their bodies as well.
"Father... I feel light, and... pretty?" one of the former Space Marines said, adjusting her oversized armor.
One by one, the mighty Thousand Sons were transformed into a legion of anime mage girls.
Agnes rubbed her temples as she looked over the newly transformed legion. "Let's see... Marisa, Nobara, and... is that a magical pony?"
Realizing Magnus was now practically swimming in his old, giant armor, Agnes dug through her stash and pulled out a spare set of her own clothing, tossing it to her.
"AHRIMAN!!!!" Magnus suddenly screamed, her new voice ringing out.
She lunged through the crowd, tackling Ahriman who was now a silver-haired girl—along with the rest of the Thousand Sons who had helped cast the Rubric.
After giving them a thorough beatdown, Magnus walked back over, dusting off her new outfit. "Mother... I thank you for saving my sons."
Agnes didn't say a word. Instead, she slowly grab a belt and smack Magnus face.
SMACK!
Magnus stumbled back, clutching her cheek in complete shock. "M-Mother?"
"It's punishment time," Agnes said coldly, folding the belt in half and snapping it with a dangerous, terrifying smile.
"...Oh. My sons, protect me!!!" Magnus shrieked, turning on her heel and sprinting away as fast as her new legs could carry her.
"Tsk, tsk, tsk. I am very disappointed in you, Magnus!" Agnes called out, hovering effortlessly after her while snapping the belt rhythmically in her hands. "You're supposed to be the smartest of all the Primarchs, but it seems you severely lack wisdom!"
"I am sorry, Mother! Forgive me!" Magnus cried, dropping to her knees and sliding across the pavement in surrender.
"It's too late for apologies!"
"AHHHHH!!!!"
--
Meanwhile in terra...
"Mhm... Was that magnus?" The emperor said.
"Eh nevermind." He said before focusing on the webway his making.
--
Meanwhile in the warp...
"Is this a joke?" Tzeech said.
While the other chaos gods laugh at tzeech anger and misfortune.