04. Gathering Storm Before the Invasion

The Calm Before the Assault

The Thirteenth Black Crusade does not begin without warning.

Before the main invasion, smaller events spread across the Cadian Gate and nearby regions.

These may include:

• Increased Chaos raids

• Missing patrols

• Cult uprisings

• Unusual Warp storms

• Sabotaged supply depots

• False military orders

• Disrupted astropathic messages

• Refugees from frontier systems

• Xenos movements

• Reports of Black Legion envoys

No single event proves that a crusade is coming.

Together, they form a pattern.

Imperial Preparations

Cadia is never truly at peace.

Its armies train constantly, fortresses maintain readiness, and commanders expect invasion.

As the threat grows, Imperial authorities may:

• Mobilize reserve regiments

• Reinforce orbital defenses

• Inspect pylon sites

• Increase naval patrols

• Secure ammunition depots

• Investigate suspected cults

• Restrict civilian movement

• Request outside reinforcements

• Prepare evacuation plans

• Establish emergency command posts

These actions protect Cadia but also strain its population and resources.

Incomplete Mobilization

The Imperium cannot respond instantly.

Orders travel slowly. Reinforcements may be delayed by Warp conditions, bureaucracy, or conflicts elsewhere.

The Departmento Munitorum must redirect troops and supplies from other fronts. The Imperial Navy must decide which routes deserve protection. Governors may resist losing local forces.

Cadia can be heavily fortified and still lack what it needs.

Gathering Forces of Chaos

Within and around the Eye of Terror, Chaos forces begin assembling.

The gathering may include:

• Black Legion fleets

• Traitor Legion warbands

• Renegade Astartes

• Traitor Guard

• Cult armies

• Dark Mechanicum vessels

• Chaos Knights

• Traitor Titans

• Daemonic hosts

• Pirates and mercenaries

These forces do not gather peacefully.

They bargain, threaten, raid one another, and compete for command.

Abaddon’s challenge is not merely assembling an army. It is keeping that army pointed toward the Imperium.

Hidden Staging Grounds

Not every Chaos force waits openly inside the Eye.

Warbands may prepare from:

• Abandoned systems

• Captured stations

• Daemon worlds

• Space hulks

• Pirate ports

• Hidden Warp routes

• Compromised Imperial worlds

• Secret cult strongholds

Finding and destroying one staging ground can delay part of the invasion without ending the larger threat.

Portents

The coming war may be foreshadowed through:

• Shared nightmares

• Astropathic screams

• Distorted stars

• Machines activating without command

• Unexplained mutations

• Recurring symbols

• Sudden acts of religious frenzy

• Psykers speaking the same words

• Dead worlds broadcasting old messages

• Blackstone structures behaving strangely

Not every portent must come directly from Chaos.

Some may result from the pylons, Necron systems, frightened psykers, or the hidden Tzeentchian conspiracy.

The Battle of Tyrok Fields

The Battle of Tyrok Fields is an important early confrontation on Cadia.

Traitor forces strike before the full invasion, testing Cadian readiness and revealing that organized enemies are already operating close to the world’s defenses.

The battle may involve:

• Traitor Guard

• Chaos Space Marines

• Cadian armor

• Artillery

• Air support

• Sabotage

• Hidden cult cells

• Conflicting intelligence

Its exact scale can be adjusted to fit the campaign.

What matters is that Tyrok Fields proves the threat is more organized than many officials believed.

Lessons from Tyrok Fields

The battle may reveal:

• Enemy knowledge of Cadian defenses

• Compromised communications

• Unexpected traitor equipment

• Black Legion coordination

• Cult infiltration within supply lines

• Gaps in Imperial command

• Signs of a larger invasion

• Evidence connected to the Fractured Sigil

Victory at Tyrok Fields may still conceal deeper failure.

A defeated enemy force may have completed reconnaissance, planted agents, or drawn defenders away from another target.

Political Doubt

Not every Imperial authority accepts the evidence.

Some may argue that:

• Chaos raids are routine

• Cadia is already sufficiently defended

• Reinforcements are needed elsewhere

• Reports are exaggerated

• The Inquisition is causing panic

• The Navy is protecting its own interests

• Local commanders seek prestige

• Cult investigations are politically motivated

These doubts need not come from traitors.

Officials may be acting from limited information, competing responsibilities, or genuine fear of wasting scarce resources.

Conflicting Orders

As pressure increases, characters may receive contradictory instructions.

Examples include:

• Hold a fortress or evacuate it

• Protect a pylon or destroy nearby machinery

• Escort refugees or prioritize ammunition

• Arrest a suspect or preserve their cover

• Recover intelligence or prevent its spread

• Reinforce Cadia or investigate a distant system

Such conflicts allow player choices to shape preparation for the invasion.

The Five Starting Locations

Each starting location can encounter the approaching war differently.

Gate of Arrival, Cadia:
Reinforcements, refugees, inspections, military tension, and signs of infiltration.

Scavenger’s Rest, Necromunda:
Black-market weapons, missing shipments, cult recruitment, and stolen military supplies.

Krell’Sharr Platform:
Rumors from distant traders, unusual xenos movements, mercenary contracts, and intercepted cargo.

Hall of Supplicant, Mendrengard:
Warband mustering, Dark Mechanicum production, political struggles, and preparations for departure.

Imperator Illuminatio:
Sealed intelligence, contradictory Inquisitorial orders, suspected infiltration, and investigations linking separate incidents.

These connections should create different paths into the same wider crisis.

No Fixed Countdown

The campaign should not require the invasion to begin after a set number of sessions.

Instead, Franz can advance the threat when:

• Major quests are completed

• Important clues are ignored

• Players travel far from the Gate

• A faction gains an advantage

• A dramatic escalation suits the story

• The party chooses to accelerate events

Preparation can change the invasion’s timing, strength, and targets.

Player Influence

Characters may alter the coming war by:

• Protecting supply routes

• Exposing cult networks

• Saving commanders

• Securing pylon research

• Destroying staging grounds

• Recruiting allies

• Delaying Chaos fleets

• Resolving Imperial rivalries

• Recovering lost intelligence

• Warning threatened worlds

No single action should prevent the entire crusade.

Several successes may significantly improve Imperial readiness or weaken one part of Abaddon’s plan.

D&D 5e Narrative Use

This period can use:

• Investigation

• Espionage

• Military missions

• Escort quests

• Political negotiation

• Sabotage

• Battlefield encounters

• Exploration

• Faction reputation

• Time-sensitive choices

Escalation should be visible through changing environments, rumors, military activity, and faction behavior.

The Gathering Storm in Play

This lore can support adventures involving:

• Investigating Tyrok Fields

• Escorting reinforcements

• Protecting a supply depot

• Hunting cult infiltrators

• Recovering intercepted orders

• Exploring a hidden staging ground

• Convincing skeptical officials

• Repairing a damaged pylon site

• Tracing weapons from Necromunda

• Preventing rival Imperial forces from withholding aid

The invasion has not yet begun.

That is what makes this period important.

The choices made before the first great assault may determine who is prepared when it arrives.