The Great Rift (Cicatrix Maledictum) Explained

The Great Rift — known formally as the Cicatrix Maledictum — is a galaxy-spanning tear in reality that ripped the Milky Way in half during the closing days of the 41st Millennium. Created by the catastrophic destruction of Cadia and the collapse of the Cadian Pylons, the Great Rift is the single most significant change to the Warhammer 40k setting in the game’s history, fundamentally altering the balance of power between every faction in the galaxy.

What Is the Great Rift?

The Great Rift is an immense wound in the fabric of realspace where the Warp bleeds directly into the material universe. Stretching from the Eye of Terror near the galactic northwest to the Hadex Anomaly in the galactic east, it effectively divides the Milky Way into two halves:

Imperium Sanctus — the “lit” side, where the Astronomican (the Emperor’s psychic beacon) can still be seen, and where Terra, Ultramar, and most major Imperial institutions remain
Imperium Nihilus — the “dark” side, cut off from the Astronomican’s light, where Warp travel is nearly impossible and billions of Imperial citizens have been abandoned to darkness

The Rift is not merely a Warp storm. It is a permanent, physical reality — a canyon of screaming madness visible to the naked eye as a lurid scar across the night sky from every world in the galaxy. Daemons pour from it endlessly. Worlds near its edges are consumed by Warp phenomena. And it is slowly, inexorably growing.

The Cicatrix Maledictum

The formal Gothic name for the Great Rift — Cicatrix Maledictum, meaning “Accursed Scar” — reflects its nature. It is not an opening but a wound — a place where reality has been torn and cannot heal. The Rift follows existing lines of Warp instability: the Eye of Terror, the Maelstrom, and dozens of smaller Warp rifts that have existed for millennia were connected and amplified into a single continuous tear.

The Rift is not uniform. In some areas, it is relatively narrow and can be crossed by skilled Navigators. In others, it is so wide and violent that nothing can pass through. Some regions experience “calms” where the Rift weakens temporarily, while others are wracked by Warp storms that make the Eye of Terror look tame.

How the Great Rift Was Created

The 13th Black Crusade

Abaddon the Despoiler’s 13th Black Crusade was the culmination of ten thousand years of warfare against the Imperium. Unlike his previous twelve crusades — each of which had specific, limited objectives — the 13th was a full-scale invasion aimed at destroying the fortress world of Cadia.

Cadia was more than just a fortress. It guarded the only stable route out of the Eye of Terror, and its surface was covered with ancient Pylons — mysterious devices of Necron origin that suppressed Warp activity and kept the Eye of Terror contained. As long as the Pylons stood, the Eye could not expand.

The Fall of Cadia

The battle for Cadia was the largest military engagement in the 41st Millennium. Billions of Imperial Guard, Space Marines, Sisters of Battle, and other forces defended the world against an equally massive Chaos onslaught. The fighting was apocalyptic.

In the end, when conventional warfare could not break Cadia’s defenses, Abaddon used the Blackstone Fortress Will of Eternity as a kinetic weapon — crashing it directly into the planet’s surface. The impact cracked Cadia apart and destroyed the Pylons.

With the Pylons gone, there was nothing holding the Eye of Terror in check. The Warp erupted.

The Birth of the Rift

The destruction of the Cadian Pylons triggered a chain reaction across the galaxy. Every Warp rift, every weak point in reality, every suppressed tear suddenly ripped open. The Eye of Terror expanded explosively, linking with the Maelstrom and dozens of other Warp anomalies to form a continuous scar across the entire galaxy.

Simultaneously, the Eldar god of the dead, Ynnead, partially awakened. The birth-scream of a new god and the death-scream of a galaxy’s worth of Warp barriers combined to create the Cicatrix Maledictum — the Great Rift.

Effects on the Galaxy

The Great Rift’s creation was the most catastrophic event since the Horus Heresy. Its effects include:

Warp travel disruption — Warp routes throughout the galaxy were scrambled. Many became impassable. Journeys that once took weeks now take months or years
Psychic disturbances — The number of psykers born across the galaxy increased dramatically. So did the number of daemonic possessions, psychic awakenings, and Warp-related catastrophes
Daemon invasions — Daemons poured through the Rift in unprecedented numbers. Worlds that had never seen a daemon were suddenly fighting for survival against Warp entities
Astronomical navigation — The Astronomican is blocked or distorted by the Rift, making navigation in Imperium Nihilus nearly impossible
Communication breakdown — Astropathic communication across the Rift is unreliable at best, impossible at worst

Imperium Nihilus — The Dark Imperium

The half of the Imperium on the far side of the Great Rift — Imperium Nihilus, or the Dark Imperium — is in a state of near-total collapse. Without the Astronomican, Warp travel is incredibly dangerous. Without astropathic communication, worlds cannot call for help. Without reinforcements from Terra, every system is on its own.

Key developments in Imperium Nihilus include:

Baal and the Blood Angels — Commander Dante was appointed Regent of Imperium Nihilus by Guilliman, tasked with holding together what remains of Imperial authority on the dark side
The Nachmund Gauntlet — One of the few semi-stable passages through the Rift, heavily contested by all factions
Widespread chaos — Many Imperial worlds have fallen to Chaos, xenos invasion, or simple anarchy. Others have developed independent governments or turned to heresy out of desperation
The emergence of new threats — Cut off from Imperial authority, new powers are rising in Nihilus, from petty warlords to Chaos empires

The Noctis Aeterna — The Blackout

The moment the Great Rift opened, the entire galaxy was plunged into a period of absolute darkness known as the Noctis Aeterna (the Blackout). For a period of indeterminate length — time itself was distorted — the Astronomican went dark. Every world in the Imperium was cut off from every other. Warp travel was impossible. Communication ceased.

The Noctis Aeterna lasted for different durations in different locations — some worlds experienced it for days, others for years, and a few may still be trapped in it. During this period, countless worlds fell to daemon invasion, xenos attack, or internal collapse. The death toll was incalculable.

The Astronomican eventually returned — though weakened and intermittent on the Nihilus side — but the damage was done. The Imperium that emerged from the Blackout was fundamentally broken, held together only by the return of Roboute Guilliman and the deployment of the Primaris Marines.

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Impact on Each Faction

The Imperium

The Imperium was split in half, losing communication with and control over nearly half its territory. Guilliman’s Indomitus Crusade — a massive military campaign to stabilize the Imperium and deploy Primaris reinforcements — has been the defining Imperial response, but it is a desperate holding action, not a reconquest.

Chaos

For the forces of Chaos, the Great Rift is the greatest victory since the Horus Heresy. Daemon invasions are easier than ever. Chaos worship is spreading. The Rift itself feeds the Chaos Gods with the suffering and terror of trillions. Abaddon has achieved what Horus could not — a permanent, expanding beachhead of Chaos in the material universe.

The Eldar/Aeldari

The Rift threatens to overwhelm the Eldar’s already precarious existence. Their Craftworlds, Webway passages, and Exodite worlds are all at risk from Warp incursion. The partial awakening of Ynnead offers hope, but the faction is more divided than ever on how to respond.

The Orks

The Orks are thriving. More enemies to fight, more chaos (literally) to enjoy, and more opportunities for the biggest WAAAGH! in history. The Rift has disrupted some Ork empires but energized others.

The Tyranids

The Hive Mind appears to be using the disruption caused by the Rift to launch new tendrils of invasion into weakened Imperial space. The Tyranids are a biological rather than Warp-born threat — the Rift’s Warp distortions are less directly dangerous to them than to other factions.

The Necrons

The ancient Necrons view the Great Rift with cold fury. The Pylons that held the Eye of Terror in check were of Necron construction, built during their ancient war against the Old Ones and the Warp. The Rift’s creation represents a catastrophic failure of their ancient containment systems. Some Necron dynasties are working to build new pylons or find ways to close the Rift.

The T’au

The T’au Empire, located in the galactic east, is largely on the “safe” side of the Rift but is now encountering Warp phenomena for the first time. Their lack of psychic sensitivity offers some protection, but they are woefully unprepared for the reality of Chaos.

The Great Rift in the Current Setting

As of the current Warhammer 40k timeline (the Era Indomitus), the Great Rift defines the setting:

The Indomitus Crusade continues, with Guilliman deploying forces across both halves of the Imperium
The Rift is slowly expanding in some regions, contracting slightly in others
New Warp storms are spawning from the Rift, creating secondary tears
The Nachmund Gauntlet remains a critical strategic chokepoint, fought over by all factions
Whether the Rift can ever be closed is an open question — it may require the full power of the Emperor, the Necron Pylons, or the Eldar god Ynnead to seal

The Great Rift has transformed Warhammer 40k from a setting in stasis to one in active crisis. The Imperium is no longer merely declining — it is actively breaking apart. And for the first time in ten thousand years, that decline may be irreversible.

Frequently Asked Questions

Can you travel across the Great Rift?

Yes, but it is extremely dangerous. A few stable passages exist, notably the Nachmund Gauntlet. Skilled Navigators can find temporary gaps. Some factions (Eldar via the Webway, Necrons via Dolmen Gates) have alternative methods that bypass the Rift entirely.

Is the Great Rift the same as the Eye of Terror?

No. The Eye of Terror is one end of the Great Rift — an ancient Warp rift that existed for ten thousand years before the Rift formed. The Great Rift connected the Eye of Terror to other Warp anomalies across the galaxy, creating a single continuous tear. The Eye is a region within the Rift, but the Rift extends far beyond it.

Could the Great Rift be closed?

Theoretically, yes — the Necron Pylons were holding the Eye of Terror in check for millennia. If enough new pylons could be constructed or activated, the Rift might be suppressed. The Eldar god Ynnead might also play a role. But practically, closing the Rift would require a level of cooperation and power that the galaxy’s factions seem incapable of mustering.

What caused the Astronomican to go dark during the Noctis Aeterna?

The exact mechanism is debated. The most likely explanation is that the Rift’s creation caused such violent Warp disturbance that the Astronomican’s signal was drowned out, like a candle in a hurricane. The Emperor did not die — his light was simply overwhelmed temporarily by the birth-scream of the Rift.

When did the Great Rift open in Warhammer 40k?

The Great Rift opened at the very end of the 41st Millennium, around 999.M41, right after Cadia fell to Abaddon’s 13th Black Crusade. Its opening began the Noctis Aeterna, after which the timeline moved into the Era Indomitus of the 42nd Millennium. In real-world terms, Games Workshop introduced it in 2017 with the Gathering Storm books that led into 8th Edition.

Is the Great Rift still growing?

Yes, in places. The current lore describes the Rift as slowly expanding in some regions while narrowing slightly in others, and new Warp storms keep spawning from it. It is a permanent tear rather than a passing storm, so worlds near its edges are always at risk of being swallowed. Whether it can ever be closed remains one of the setting’s big open questions.

The Great Rift — Warhammer 40k’s Galaxy-Splitting Event