Next, we will introduce the true "best member" of the entire rebellion—one could say he is the rebellion's undisputed MVP.
The Crimson King, Magnus.
If not for his actions, this rebellion, even at its most ferocious, could have been easily handled as long as The Emperor was free to act.
If not for his series of actions, even if Horus had gathered nine Legions, as long as The Emperor was free to act, this rebellion would have amounted to little more than a slightly larger Policing Action.
This is the ultimate example of "good intentions leading to disaster," a story of how wisdom was blinded by arrogance, ultimately leading to ruin.
The camera zooms in, focusing on Prospero's central city—Tizca.
It was the City of Light.
Pyramid-shaped buildings pierced the sky, massive crystal prisms refracted the star's brilliance, and the streets were walked not by crude soldiers, but by robed scholars and philosophers holding scrolls.
Here, knowledge was currency, and psychic power was the tool.
And at the center of it all, atop the highest pyramid, sat a giant.
He had skin as red as flame, and a body larger than any mortal.
He wore magnificent armor adorned with Golden Scarabs and ancient runes, and behind him, a cloak woven not merely of fabric, but of flowing psychic energy.
But what was most striking was the single eye on his face, which was full of wisdom yet slightly arrogant.
It was not a physical monocular state, but a right eye that had lost its orb, leaving only an empty socket, and a left eye that shimmered with infinite arcane light.
Magnus, Primarch of the Fifteenth Legion, the Thousand Sons.
Like his Brothers, when he was still an infant, he was used as a bargaining chip by the Chaos Gods, swept away from the gene-labs of Terra, and scattered across the corners of the galaxy.
Fate—or perhaps Tzeentch's scheme—brought him to Prospero.
The screen flashes back, showing the arrival of the infant Magnus.
The red infant descended from the sky, crashing onto Prospero's main plaza like a comet.
For this Planet, filled with exiled Psykers, Mutants, and scholars, his arrival was not a disaster, but a miracle.
Because Prospero was suffering an Existential Catastrophe.
A type of Warp predator called the "Soul Devourer," a creature resembling a giant wasp, specialized in feeding on the brains of Psykers.
They built nests within the Planet's psychic layer, harvesting the population of Prospero like a crop.
The young Magnus displayed astonishing talent.
He required no schooling; he was born knowing how to harness the power flowing through the air.
He called it "the Warp"—the same Warp that others in the Imperium spoke of with dread.
To Magnus, it was not Hell; it was an ocean of knowledge, a source of power.
He grew quickly, his physique becoming immense, and his wisdom surpassing all the sages on the Planet.
He taught the people of Prospero how to construct shields using psychic energy, and how to transform mental power into swords.
He led his people in a counterattack.
In that historic battle, Magnus was like a god descended; his psychic flames burned through the sky, completely driving out the Soul Devourers that had plagued the people for centuries.
He became the King of Prospero.
He established Tizca, built the Great Library, and dedicated himself to collecting knowledge from across the galaxy.
He firmly believed that only knowledge could allow humanity to evolve, and only by mastering psychic power could humanity truly become the master of the galaxy.
This was Magnus's essence: scholar, Deliverer, and an extremely confident Psychic Master.
However, the seeds of tragedy had already been sown.
Because his confidence was built upon a half-understood knowledge of the dimension called the Warp.
He thought he was merely picking up shells on the beach, unaware that a pair of eyes in the abyss was watching him greedily.
The scene shifts; the timeline advances to the Great Crusade era.
The Emperor found him.
The scene was remarkably harmonious. When The Golden Emperor descended upon Tizca, there was no conflict between him and Magnus. The two instantly confirmed each other's identities through psychic communication.
The Emperor looked at his red son, his eyes filled with relief. For among all the Primarchs, only Magnus had inherited his vast, oceanic psychic talent.
If Horus was The Emperor's heir as the "Warmaster," then Magnus should have been The Emperor's heir as the "Guide of Humanity" and the "Master of the Webway."
The Emperor even showed Magnus some truths about the Warp, and gave him the sternest warning:
"Look into the abyss, but do not leap into it. Utilize this power, but do not trust it."
Magnus nodded in agreement.
But the voice deep inside him whispered: "Father is too conservative. He doesn't know how much I already control; he doesn't know this power can actually be tamed."
This was arrogance.
This arrogance continued to swell in the years that followed.
Magnus took command of the Fifteenth Legion, the Thousand Sons.
This was a Legion whose members, like him, were all Psykers.
But they suffered from a terrible Genetic Curse—the "Flesh Change."
Without warning, the warriors' bodies would mutate, transforming into mindless masses of flesh.
To save his sons, Magnus made the first fatal bargain of his life.
Deep within the Warp, he reached an agreement with an "entity composed of pure energy."
He sacrificed his right eye in exchange for a Spell to halt the Flesh Change.
The mutation stopped. The Thousand SonsLegion was saved.
Magnus considered it a profitable deal. He thought he had only paid the price of an organ.
Little did he know, that was the first Collar placed upon him by the Lord of Change, Tzeentch.
As the Great Crusade progressed, the Thousand SonsLegion was invincible, relying on powerful Psychic Tactics.
They could make enemy forces slaughter each other without firing a single shot; they could foresee the future and manipulate fire and lightning.
But this aroused fear and disgust among his other Brothers.
Especially Mortarion and Leman Russ. In their view, this was Sorcery—a filthy, uncontrollable power that would eventually destroy everything.
The conflict fully erupted at the Council of Nikaea.
It was a Judicial Council convened by The Emperor regarding whether the Legions should be allowed to use psychic powers.
Magnus spoke passionately at the council, defending his position with flowery rhetoric, claiming that knowledge was innocent and power itself had no inherent good or evil. He attempted to prove that psychic power was the ladder of human evolution.
But he failed.
The Emperor looked at his endlessly bickering sons, looked at the tragedies caused by uncontrolled psychic power, and finally made his judgment:
The Edict of Nikaea.
"Henceforth, the use of Sorcery by any Legion is forbidden. The Librarian Departments are to be dissolved. Violators shall face destruction."
The Emperor's command was absolute.
Magnus outwardly submitted. He returned to Prospero with the Thousand SonsLegion, but he did not cease his research.
On the contrary, he became even more obsessive.
"Father is wrong. Russ and Mortarion, those barbarians, have blinded Father's eyes."
"I must prove I am right. If only I can achieve a great enough feat, if only I can save the Imperium using psychic power, Father will understand my earnest intentions."
Driven by this feeling of "grievance" and the desire to "prove himself," Magnus tirelessly projected his consciousness across the void from the pinnacle of Prospero's highest pyramid, monitoring the movements of the galaxy.
It was at this very moment that the wheel of history rolled to the edge of the cliff.
The Tragedy of Davin occurred.
At this time, Horus was lying critically wounded in a Temple on Davin, his soul wandering in the Warp, being led step by step toward corruption by the illusions set up by Erebus and the Chaos Gods.
Meanwhile, on distant Prospero, Magnus, who was traveling through the Warp, keenly sensed this disturbance.
It was a storm in the Warp, the echo of the Chaos Gods' mad laughter.
Magnus saw it.
He was the first, and the only person in the entire galaxy, to see the truth at that moment.
He saw Horus's hesitation, he saw Erebus's lies, and he saw how the future flames of war would devour the entire Imperium of Man.
In that moment, Magnus's heart was filled only with fear and anxiety.
"No! I must stop all of this, even if it costs me everything!"
He tried to use his psychic abilities to rush into that illusion; he tried to awaken Horus.
"Horus! That is a lie! That is a trick of the Warp! Do not listen to that dead man!"
He manifested within the illusion, attempting to pull back his brother who was walking toward the abyss.
But he failed. Horus's ambition and hatred for The Emperor had been ignited; he rejected Magnus's advice and chose to embrace Chaos.
Magnus was ejected from the illusion.
His physical body on Prospero jolted awake, cold sweat soaking his entire body.
"Horus has betrayed us..."
This thought exploded in his mind like a clap of thunder.
That was the Warmaster! The commander of nine Imperial Legions! If Horus raised the banner of rebellion, it would be a catastrophe!
The Emperor must be warned!
His Father must know this news immediately, right now, without any delay!
Conventional methods were already too slow.
Warp storms were sweeping across the galaxy; Astropathic Communication was severely disrupted, and ship travel was slower than a snail.
By the time the news reached Terra, Horus's fleet would probably already be on their doorstep.
Magnus looked up at the starry sky, a look of desperate resolve flickering in his single eye.
"There is only one way."
"I must use the forbidden Sorcery. I must project my mind directly to the Terra Imperial Palace and tell Father this news face-to-face."
"Yes, this violates the Edict of Nikaea. Yes, this uses Sorcery."
"But compared to a disaster like the Horus Heresy, what is a mere prohibition? As long as Father knows the truth, as long as I save the Imperium, he will surely forgive me, perhaps even reward me!"
"This is the perfect opportunity for me to prove the value of psychic power!"
Within this closed loop of logic, Magnus convinced himself. He was not just a messenger, but a child desperate for his Father's approval.
He gathered the most powerful Sorcerers of the Thousand SonsLegion.
In the center of the City of Light, the massive ritual began.
Countless sacrifices were offered, and vast psychic energy converged upon Magnus like a flood.
He drew his soul from his body, transforming into a crimson meteor capable of traversing time and space, plunging headlong into the maelstrom of the Warp.
He had only one target: Holy Terra, the dungeon beneath the Imperial Palace.
Because he knew his Father was there.
Magnus's psychic form sped through the Warp; he was like a sharp sword, cleaving through the mists of Chaos.
Soon, he saw Terra.
But he also saw an obstruction.
At the boundary between reality and the Warp near the Terra Imperial Palace, there was an incredibly sturdy, incredibly precise Psychic Barrier constructed personally by The Emperor.
That barrier protected the Imperial Palace, and it also protected the top-secret project called the Webway.
Magnus did not know all the details of the Webway Project. He only knew that a wall blocked him.
He could not enter.
"Father! Let me in! I have intelligence of the utmost urgency!"
Magnus frantically pounded on the outside of the barrier, striking it with psychic force, but the barrier remained completely still. It was the crystallization of The Emperor's wisdom, the last line of defense for the Physical Universe.
Time passed minute by minute.
Magnus grew more and more anxious. Horus was gathering his armies, and every second of delay could lead to the destruction of countless Planets.
"I must break it! For the sake of the Imperium!"
Just as he was on the verge of despair, a tempting voice sounded in his ear.
It was the voice of Tzeentch, but at this moment, it sounded so "helpful."
[Do you require assistance, Magnus?]
[Do you wish to save your Father, save your Imperium?]
[This wall is too thick; you cannot open it with your strength alone. But if you accept just a little... insignificant amount of power, together we can push this door open.]
[Come, accept this power. For justice, for loyalty.]
Normally, a calm Magnus might have noticed the trap.
But now, his mind was filled with "saving The Emperor," "earning merit," and "proving himself."
He did not hesitate.
"No matter who you are! Give me the power! Anything to let me see my Father!"
Magnus opened his soul, accepting the boundless, vast power that flowed from the depths of the Warp.
That power surged into his body, causing his psychic form to swell and burn, becoming stronger than ever before.
He felt invincible.
He looked at the Psychic Barrier before him, set up personally by his Father and protected Terra for countless ages, and raised his fist, charged with destructive energy.
"Open... for me!!!"
[BOOM—!!!]
This strike was not just a physical impact; it was the shattering of a concept.
The defense meticulously constructed by The Emperor, empowered by the might of Tzeentch, shattered like glass.
Not only did the barrier break.
But along with it, the underlying structure of reality behind the barrier, the precision machinery maintaining the Webway's stability, the cooling systems of the Golden Throne that The Emperor had poured countless efforts into... all instantly overloaded, melted down, and exploded.
A massive, unhealable rift was forcibly torn open in the Underground Room of the Terra Imperial Palace.
Magnus had done it.
He had successfully broken through.
Filled with the joy of victory and the eagerness of "I'm finally inside," this crimson psychic storm rushed into the Imperial Palace's Subterranean Hall.
The scene he originally envisioned was this:
He would appear before his Father and loudly announce the news of the Horus Heresy.
His Father would be shocked, then grateful, praising his quick wit and strength, realizing how important psychic power was, and then Father and son would stand united to fight the traitor.
However, when he truly stood still and saw everything around him, that joy instantly froze on his face.
What he saw was not gratitude.
It was hell.
Because with the shattering of that barrier, the endless, ravenous Warp Daemons that had been pressing against the Webway, like a flood finding an outlet, poured madly and roaringly into the Terra Imperial Palace through the great hole Magnus had smashed open.
Countless Custodian Guards, Sisters of Silence, and Adeptus MechanicusPriests were instantly overwhelmed by the tide of Daemons.
The precise Webway entrance had turned into a volcano spewing Death and madness.
Terra's entire Psychic Network was screaming.
The originally hopeful "Human Webway Project," the grand blueprint that could have allowed humanity to completely escape the threat of the Warp, instantly became an express train straight to hell.
To plug this hole, to prevent Terra from becoming a second Eye of Terror, The Emperor had to use all his strength, pinning himself firmly to the Golden Throne, using his mental power to fight the endless tide of Daemons.
From then on, he could never leave the Throne, not even half a step.
Magnus's psychic form floated motionlessly in mid-air.
He looked at the devastated Laboratory, at the Custodian Guards fighting desperately, and at his Father, sitting upon the Throne, wracked with pain, his eyes filled with disappointment and exhaustion.
He finally realized what he had done.
In attempting to report that "the house is on fire," he had personally blown up the load-bearing wall and, for good measure, doused the fire with a ton of gasoline.
He opened his mouth, the rousing phrase he had prepared—"Father, I have brought you vital intelligence"—now caught in his throat, turning into a weak, pale whisper:
"Papa... I... I just wanted to help..."
"Horus... Horus has betrayed us..."
In this instant, all his pride, all his confidence, and all his fantasies about "being right" shattered into dust before the cruel reality.
Magnus the Red, The Crimson King, using his unparalleled wisdom and strength, achieved a feat that WarmasterHorus could not have accomplished even by gathering nine Legions—
He personally crippled The Emperor.