Thetys Rift

*"Thetys, our empires bane, cursed be you, cruel mistress of the void. She who robbed us noble heirs from Holy Terra of our worlds."*

A festering wound splits the heart of Sector Gondwana, bleeding un-reality into the cosmic void and the unholy light of the Immaterium. To all worlds of the Triumvirate, the rift is a glaring blemish crossing the firmament, its sight alone invoking strange and dangerous dreams. The light shone from the realm of souls taints the constellations with bad omens and sends writhing shadows onto their many worlds.

## The threshold of an otherworldly realm

Thetys is the name given to the Rift by local voidfarers, for their oldest legends tell of a primordial age when the rift opened into a different realm, one not yet discovered by demons and their ruinous lords. In those ages past, the rift was alive with otherworldly creatures so plentiful as life had been once during the old times in greatest of oceans on Holy Terra. And they made for good hunting and prey to the void-ward whalers, who cut their skin and bones for riches long forgotten.

But the age of aquamarine in Thetys would not last, for when the Aeldari worlds burnt, the otherworldly realm too was swept away. Its spheres were consumed in everlasting fire, fueled by the wrath of ruinous gods reborn, and of the realm was left little but slaughter and carnage.

Still, some say, a few of the elder creatures remain, older than the demons and ruinous gods possessing them. Killing one of the old leviathans is regarded a deed of great legends by the voidfarers of Sector Gondwana, for it is said to foretell good things to free a soul so old from the curses of demonic corruption.

## Astrography

### Reach into Subsectors

The Thetys Rift runs through the whole of Subsector Cambria, where its rousing edges lie closest to imperial worlds. And yet, the Cambrian Thetys Rift is merely the least fissure of a tear much greater, a storm of the empyrean enveloping Subsector Ordovichia whole. When the tides of this storm are at their highest, streaks of red and purple lightning lash out even at Subsector Ediacara's golden stars. But these remain forever unscathed, for there are powers protecting them which are older and more terrible than any demon on these distant shores of the Sea of Souls.

### Neighboring regions

Two regions are near the Thetys Rift of the Cambrian subsector.To the galactic north, the Glacial Nebula looms on the firmament, it's azure ridges forever frozen in time.Southward and to the galactic west, the Erinnyenmere lie, wild systems of the shadow fiefdom, where the Crimson Queen reigns and her corsairs make trade with the Triumvirate World Trantor and the forbidden worlds beyond.

In between those two constellations, the Unland of Cambria sets Glaive's reach and the Rift apart, a dangerous abyss of unruly tides, throwing all ships far from their course and making passage nigh impossible.

### Limes Gondwana

Along all the Thetys Rift watchtowers are arranged. In abandoned systems and on rogue worlds, near the threshold of every passage known, mighty stations were erected in times of old and manned by the vigilant watchers of the Rift. From the mighty world Trantor, the first watchers came, keepers of Subsector Cambria and vanguard of its many fleets. Monitoring the tides of the warp and holding off incursions of infested hordes, they held the first line of defense against chaos and the unknown.

Even across interstellar space, star forts, lighthouses and beacons dot the skies before Thetys, a bulwark of humanity subject to constant decay and reconstruction. The greatest of these lone fortresses are Mogontiacum, Tumunzahar, and Gahmuret. From their ports set out unending forces in a tireless crusade against the dark. Their light shines as a beacon of hope to all who come near the Thetys Rift – a safe harbor for the Emperor's loyal souls.

### Worlds lost to the warp

Closer to the edge than the Limes Worlds lie only systems and planets entirely lost to the warp. Once, these were prosperous regions, worlds of a great alliance of voidfaring fishermen, who dwelt near the otherworldly Thetys Realm and traded with many civilizations of Subsector Cambria. But as the worlds of the Aeldari were swept away, a great fire consumed the otherworldly realm as well, and the worlds were abandoned, left for the surging warp to take.

Now, the Rift is a graveyard of worlds, many broken and splintered, mere shards spread between stars. Continents ripped from their own world's core, mountains flung into space by forces unimaginable, even cities thrown into space as one litter now the skies of Thetys. Those few planets left intact are lifeless husks infested with corrupted energies, yet still holding countless artifacts of the age of aquamarine. Relics of the old hunters sometimes find their way into the populated systems, sometimes as tokens of good fortune, in other cases as portents of doom.

#### Unique Kumaforth

Amid the Rift's many long lost constellations lies a single world which held on to its remnants of the humankind. In the ruins of a civilization fallen for uncounted millennia, there persist the wild peoples of forlorn feral Kumaforth, unique sanctuary among cursed stars.

Blessed or cursed by powers unknown, life continued on the abandoned world even through the cataclysm. Between the Limes Gondwana and the abyss of Thetys, it thrived in strange ways on the planet, which was once covered by continental hives, landscapes of rockcrete and iron. Still, the surface is dominated by their tall, imposing spires, an unending forest of high gothic design, overgrown with flora and the crude settlements of its barbaric people.

Too tainted are they to ever fully return to the Imperium, and yet some lost souls of Gondwana pray to the saints of Kumaforth as a sign of survival against the highest odds.

### Uncharted regions of the Far Side

Beyond the worlds lost to the rift lie systems further still. Those constellations on the Far Side of Thetys are the uncharted regions, whom few souls ever beheld. Forced from the grasp of humanity, these have been lost for more than ten millennia.

Rare legends of these parts tell of long fallen civilizations, and ones newly arisen from the ashes of mankind and vile Xenos breeds. None have found mention more often in the tales of Rogue Traders than the elusive "Pillar Worlds" out on the western edge. A realm of great power is said to be their domain, and rumors speak of secretive trade between them and the Corsairs of Port All. Whatever is known about them with certainty, however, is buried deep in the darkness of the Erinnyenmere.

### Crossings and Passes

Few souls ever braved to cross the Rift's tides for the uncharted regions beyond. Fewer still returned sanely and lived to tell those legends wherein lies all knowledge of the Imperium about the stars out of its reach. The most adept voidfarers making the passage have long been known to be the Crimson Queen's corsairs. But they make their journeys along hidden paths, through passages held by the fiefdom alone.

Other passages are held by the great old fortress worlds, but each day passing changes their size and number. For they are little more than calm moments in the Rift's raging storm, wholly dependent on the currents of the wild void, the traveler's temper and omens of fortune.

In their passage, voidfarers are aided by Sector Gondwaners largest choirs of holy astropaths, enshrined on each station near passages newly opened. Those choirs are to send mighty calls into the cosmic night, to be heard beyond the reach of the Astronomicon, for lost travelers to find their way home.

Once the journey across such a passage is begun, the astropath's song and prayer will be the only tether of human civilization reaching back to the mighty worlds of the Imperium. From there on, any expedition or ship is truly alone, set against a night of endless shadows and malicious intellect.

## Tides of Thetys

Within the Rift Thetys rise and fall the tides of the Warp, tearing at the very fabric of reality. Distorting the continuum of space and time, they create countless singularities and cosmic horizons, cliffsides, and precipices for any ship to falter and fail. In irregular intervals every few centuries, it is these tides sparking singular events and incursions, which is known as the tides of the Thetys Rift. In these years of the tide, star maps change and the skies are re-arranged at the whims of mad gods.

### Surges

Where the tides of Thetys recede awaits an occurrence more terrible still. The storms of chaos fall silent for a few years before it comes, as though to await their master's coming in unholy awe.

The sickly glow of many hundred swallowed stars foretells the coming of a Thetys Surge, when all worlds lost to the Rift are falsely recreated, brought back to unnatural life and thrown against those standing guard.  Great flowing fills the chambers of old, spheres of lost realms growing into the kingdoms of young demons and from their gates break forth strange incursions of un-reality, warping and twisting the laws of the known world to shatter all of the Emperor's creation.

No mere demon hordes invade during a Thetys Surge, but the sheer thoughts of mad gods made manifest. On a cosmic scale, the onslaught of ruinous powers brings war upon the first dimension. All of Sector Gondwana shudders with a wailing cry when the surge breaks first against the fortresses and stars.

Three times in remembered history did a surge spring so far as to threaten the Triumvirate, three times that the faceless gods unleashed their might against its worlds in rolling thunder. Each time, the Imperium prevailed at the cost of unnumbered souls and yet the worst has not come to pass, not through heroic triumph and sacrifice, but the sheer vastness of space setting the worlds of Sector Gondwana apart. Once the momentum of the surges ceases, they collapse into themselves as fast as they have come. Only then can crusades begin to reclaim the worlds lost and rebuild the defenses of Subsector Cambria for another time.