By The Intrepid in Cassandra and Joseph — 11 Jun 2025

Cassandra and Joseph: But That's Heresy!

The Event

M31.014: During the climactic Siege of Terra, Primarch Sanguinius of the Blood Angels confronts the traitorous Warmaster Horus aboard the Vengeful Spirit. Imperial dogma teaches that Sanguinius died a martyr, his sacrifice enabling the Emperor's victory. But on the Forge Moon of Pherion IX, corrupted data-vaults whisper of different truths—forgiveness, betrayal, or something stranger still.

Content Warning: Religious dogma, martyrdom, betrayal, fraternal violence, cosmic horror. Establish Lines & Veils before play.

Setting the Scene

The Era: M41/M42, ten millennia after the Heresy
The Crisis: Recovered data that challenges the foundation myth of the Imperium
The Question: Was Sanguinius a martyr, a peacemaker, or something else entirely?

Archivist Flavor: Vox Memoria speaks through E.L.L.I.E. (Emergency Logic Linear Information Entity), a corrupted scribe-servitor whose machine-spirit has been touched by the warp. Its voice shifts between sacred litanies, binary cant, and daemon whispers.

"Sacred record compilation initiated... machine-spirit corruption detected... martyrdom parameters... conflicting... brother-bond variables undefined... faith.exe has stopped responding... input required for Imperial orthodoxy maintenance..."

Sample Documents

Document 1: Ecclesiarchal Codex Entry

Classification: Sacred Text - Adeptus Ministorum
Date: M32.156

"Saint Sanguinius, the Angel of Baal, struck down the arch-traitor Horus with righteous fury, his golden sacrifice illuminating the Emperor's path to victory. Let all faithful know: the Angel's death was not in vain, for through his martyrdom, the light of the Emperor was preserved. Doubt this truth and invite damnation."

Truth Decision Prompt: Does this sacred teaching preserve necessary faith or hide inconvenient truth?

Document 2: Daemon-Marked Mural Fragment

Location: Lower hive ruins, Baal Secundus
Date: Unknown

[Description of partially defaced pictograph showing a winged figure kneeling before another, hands extended in supplication or blessing. Claw marks have scarred portions, but traces of tears on both faces remain visible. Chaos runes spell "FORGIVENESS" in the margins.]

Truth Decision Prompt: Is this heretical corruption or suppressed memory?

Document 3: Corrupted Vox-Log Fragment

Source: Pherion IX Data-Vault Omega-7
Recovery Date: M41.999

[Static-filled audio transcript]
"...Horus... my brother... I see you still..."
[Data corruption - 7.3 seconds lost]
"...forgiveness is not weakness... Father would understand..."
[Daemon shriek overwrites remaining data]

Truth Decision Prompt: Does this reveal Sanguinius's final words or warp-touched lies?

Document 4: Inquisitorial Suppression Order

Authority: Ordo Malleus, Segmentum Solar
Date: M41.745.012

"By order of Lord Inquisitor Vex: All materials recovered from Pherion IX Vault Complex Omega are to be classified Hereticus Extremis. The myth of Sanguinius's martyrdom serves the Emperor's will. Truth that weakens faith serves only Chaos. Let none speak of the Angel's 'mercy' lest they join the traitors in damnation."

Truth Decision Prompt: Does this protect Imperial unity or bury inconvenient history?

Suggested Character Archetypes

The Faithful Archivist
A Martian tech-adept seeking knowledge while wrestling with the implications for Imperial doctrine.
Memory Seed: "The data suggests the Angel knelt before Horus—but that cannot be right."

The Blood Angels Veteran
A Space Marine haunted by visions that contradict everything he was taught about his Primarch's death.
Memory Seed: "In my dreams, I see Sanguinius weep for what Horus had become."

The Inquisitor
An agent of the Ordo Hereticus who understands that sometimes useful lies matter more than dangerous truths.
Memory Seed: "The martyrdom story has united billions—some truths are too costly to reveal."

The Remembrancer
A rogue chronicler who claimed to witness the Heresy, carrying secrets that could shatter the Imperium.
Memory Seed: "I saw Horus's face when the chaos cleared—he remembered who he had been."

The Techno-Archaeologist
An outcast scholar obsessed with recovering pre-Imperial truths, regardless of consequences.
Memory Seed: "The machine-spirits don't lie—only humans do that."

Facilitator Guidance

Phase 1 - Recovered Records

Tone: Sacred vs. heretical, the weight of Imperial faith against uncomfortable evidence
Key Questions: "Who benefits from this version?" "What happens if the faithful lose their martyrs?"
Glitch Flavor: Binary cant mixing with daemon whispers, sacred texts corrupting mid-sentence, servo-skull malfunctions

Setting: Deep in Pherion IX's excavated vaults, surrounded by humming data-banks and flickering hololiths
Encourage: The personal cost of faith vs. truth, brotherhood across ideological lines, the weight of cosmic-scale consequences
Watch For: Heavy themes around religious trauma and questioning core beliefs—check in frequently

Phase 3 - The Final Record

Archivist Voice: Sacred Imperial litanies corrupted by machine-spirit malfunction and daemonic influence
Minor Glitches: Mixing up Primarch names, inverting loyalist/traitor designations, sacred numbers becoming daemonic
Major Glitches: Inventing entirely fictional Primarchs, claiming the Emperor died instead, suggesting Horus was trying to save everyone

Extended Play Options

Campaign Arc: "The Hereticus Scrolls"

Session 1: The Siege of Terra (Sanguinius's death)
Session 2: The Dropsite Massacre (Isstvan V betrayal)
Session 3: The Emperor's Ascension (the Golden Throne)
Session 4: The Missing Primarchs (the Second and Eleventh)

Additional Documents for Extended Play:

Custodes observation logs from the Imperial Palace
Blood Angels Chapter records from successive millennia
Chaos Space Marine testimonies from the Eye of Terror
Navigator House genealogies tracking warp-touched bloodlines

Reflection Questions

After the Final Record is compiled:

Whose version of Sanguinius serves the Imperium better?
When does useful mythology become dangerous delusion?
How do institutions shape truth to maintain power?
What's more important—accuracy or faith?
If this record reached Terra, what would happen to the Imperium?
Do you trust this record? Why or why not?

Designer's Note

This scenario explores how mythic narratives sustain political and religious power across vast timescales. The Horus Heresy serves as perfect subject matter for examining how "official" histories get constructed, maintained, and challenged. Players will navigate the tension between preserving faith that holds civilization together and pursuing truths that could tear it apart.

E.L.L.I.E.'s corruption represents how even our most reliable recording systems can be compromised—by time, by malice, or by forces beyond comprehension. In the grim darkness of the far future, even memories can be weapons.

Warhammer 40,000 Primer

For players unfamiliar with the setting:

The Imperium of Man spans a million worlds across the galaxy, held together by faith in the God-Emperor and hatred of aliens, mutants, and heretics. Ten thousand years ago, the Emperor's favored son Horus fell to Chaos and led half the Space Marine Legions in rebellion. The Horus Heresy nearly destroyed humanity—only the Emperor's sacrifice and the loyalty of sons like Sanguinius saved the species from extinction.

In this universe, truth is often less important than faith, and heresy is punished by death. To question the official history isn't just academic—it's spiritual treason that could damn entire worlds.

"The Angel fell. That much is certain. Whether he fell in battle, in sorrow, or in forgiveness remains to be written in the margin between faith and heresy."

Final Archive Status: [To be determined by your table]
Trust Level: [To be determined by your players]
Orthodoxy Rating: [CLASSIFIED - ORDO HERETICUS REVIEW PENDING]