As the Vortex Illumines the Crystalline Walls of Kor-Avul-Thaa

Kor-Avul-Thaa... finest jewel in the crown of a realm of sublime glory, greatest city in the Middle Kingdoms, mayhap all the world... Its splendid walls of shimmering crystal could be seen from a hundred leagues distant, kissed by the golden rays of the sun, or caressed by the ethereal fingers of a midnight moon. Its magnificent spires and citadels, built by generations of kings from the resplendent gifts hewn from the ancient bosom of the sacred Crystal Mountains, had oft' times been the bitter envy of rival emperors, and many were the sieges which Kor-Avul-Thaa had withstood and repulsed over the centuries, for powerful sorcerers did weave great spells of protection about the dazzling towers, and none may have passed unbidden through the vast sapphirean gates of mighty Kor-Avul-Thaa...

From the Journals of Sage Daelun

The Oracle of Kor-Avul-Thaa:
The sky rent asunder... black-winged devils surge forth from the void...
A maelstrom of crimson fire burns above us... what carnage has thou wrought?
Not sword, ballistae, nor burning brand
Could e'er these walls aspire to breach,
Yet now the city's fall is nigh,
As elder rites black fiends unleash.

High Lord of the Brotherhood of Dark Elucidation (Keepers of the Forbidden Books of the First Cataclysm):
By Klatrymadon and Zuranthus, such ancient secrets we discovered within these sinistrous, worm-worn pages,
Etched with darksome glyphs and sigils, bound with fearsome spells,
An eldritch tide of stygian sorceries unfettered by the forbidden Tome of Shadows...

Now thunderous cataclysm befalls the gleaming Kor-Avul-Thaa (The mystic gate stands open!)
The Xytaxehedron held to the stars... the incantation uttered with eager tongues...
(What long-shackled powers of the elder dark have our conjurings loosed?)

By Klatrymadon and Zuranthus, the vortex blackens the stars above,
A vast plague of amorphous horrors descends to rend with fang and talon,
(As with torrents of blood the crystalline walls run red?)
And in the glooming chambers of our shadowed sanctum, we wait, half-mad with terror,
To reap the slaughterous harvest which we have sown...

The Chronicler of the Cataclysm:
And beyond the vortex, the churning black waters of the void did disgorge the Dwellers in Eternal Shadow,
And upon a horde of winged horrors, brandishing swords of ebon flame, they rode out from the Gate...
And a terrible silence fell upon Kor-Avul-Thaa...

The Echoes of the Oracle:
The sky rent asunder, black winged devils surge forth from the void...
A maelstrom of crimson fire burns above us... what carnage has thou wrought?

The Chronicler of the Cataclysm:
The Chronicles of Time speak of only two other instances when the sky did split wide and bleed forth such a torrent of horror as that which assailed Kor-Avul-Thaa... One of those times was the fateful eve when the moon burned black over ancient Lemuria, as a legion of ravening fiends emerged from the Outer Darkness to visit catastrophe upon that realm... And the other... the other manifestation of such a staggering cosmic evil is recorded only in the ancient Scrolls of the Third Circle, a dark collection of terrifying blasphemies which was believed to have been burned by the Order of Kl'aa at roughly the same time as the first Tome of Shadows was discovered deep within the Black Pyramid... These scrolls speak disturbingly of visitations to our earth by creatures from a terrible place known as the Black Galaxy... creatures which were able to span the vast expanses of time and space separating our world from theirs in their great dark chariots, bringing pestilence and carnage whenever they set foot upon the earth... And yet, the scrolls also speak of the Others, known by some ancient, long-dead tribes as the Travelling Ones... beings who did stand against the denizens of the Black Galaxy and wage war with them across the nighted void. It is said that the Travelling Ones sailed the star-seas in huge silvern spheres ringed with a myriad pulsing lights, and that in a great battle they drove their shadowy foes back to the Black Galaxy... but at a great cost... The Travelling Ones were drained of their cosmic powers and cast into a deep slumber, and some say that they remain here still, hidden in mysterious, secret places, awaiting the time of their reawakening. It was ascertained by those mages who found the Tome of Shadows that certain gateways existed linking our world and the Black Galaxy, just as maps carved into the stone walls of ancient tombs displayed the pathway to the terrifying realm through the eternal blackness of the void... and within the sinister pages of the dread book were the arcane keys... the rites to open wide these gates and give the dark wanderers beyond the freedom to roam the earth once again...
And the darkling lords did descend upon Kor-Avul-Thaa to claim their splendid prize, and enthrone themselves within the glittering walls...

The Echoes of the Oracle:
Not sword, ballistae, nor burning brand
Could e'er these walls aspire to breach,
Yet now the city's fall is nigh,
As elder rites black fiends unleash...

The Brotherhood:
By Klatrymadon and Zuranthus, in Kor-Avuk-Thaa, darkness reigns eternal...
Nevermore shall the city glimmer, for now the crystalline walls gleam black...
Ever black...

And so it was that the bedazzling and splendid Kor-Avul-Thaa did become the City of Shadows, a sinister fortress of elder fiends and fearsome beasts, unleashed by the meddlings of mortals aspiring to dark thresholds of forbidden knowledge and arcane power, a nightmare city shunned and feared by all. And not since the sinking of Atlantis was the fall of a realm so sorely lamented...