Shadow of the Whale
In 0BD, one of the most catastrophic events in Riiga took place. A vast black storm swept across half the known world, almost wiping out entire civilisations and causing the reshaping of most in its wake. According to many historical records, the source of the storm was a colossal magical creature somewhat resembling a black whale drifting menacingly through the sky, encircled by a raging, destructive storm. Invading forces of monsters coordinated with the event at most locations, leading many to believe the same being who is responsible for monsters was also responsible for the Darkness. The event mostly affected the Mintar Empire, the Xilou Hoqomer, the Yvabira Kingdom, and the Six Kingdoms of Nor. Cities that were hit include most of the cities in Nor; Tjynas, Undhul, and Khamis in Mintar; Zirer and Euxafi in Xilou; and most cities in Yvabira.
The storm is believed to have formed in the Sea of Ash, between Armalia and Jindiara. It travelled west across Karber, and Sheber, crossed between the Karber Sea and Simber, and across the northern end of Seleru, where it circled around and swept across Nor from west to east, across Ideitess and Bymir, and it dissipated somewhere around Bymir. There are records of the Darkness occurring in Batur, but the Baturun people at the time had very little in the way of reliable written records. It is without a doubt that the storm never made it to Temanea.
Those who had warning of its arrival gathered armies and their best artillery to help against the encroaching monster forces, but no weapon could even reach the whale. Some accounts of battles don't even have reports of any entity being spotted amidst the raging storms. Though some armies did manage to hold legions of monsters at bay for a time, the ever-increasing black storm eventually overpowered every force humans could gather and they were all defeated. The monsters did not take over the conquered cities and kingdoms, however. When the storm passed, the monsters dealt as much damage as they pleased, and then they withdrew back into the depths. Despite several civilisations collapsing, large numbers of populations themselves survived. It seemed more of an attack against civilisation itself than an attempt to kill everyone.
The devastation was so immeasurable that the primary calendars marked the following year 1AL (After Light), and made dates before count backward under BD (Before Darkness). Though not all peoples use this calendar, it is the most widely used dating system in Riiga.
But not all that happened during the Darkness was tainted with despair: The Xelevikenar called Veriviet appeared during the Darkness, commanding the monster attack against the ancient city of Arngos in southern Nor. So great was the attack and Veriviet's power that Arngos was razed and the land became so scarred that the city was not rebuilt. Veriviet was slain by the high priest of the Kingdom of Elecia -- a man known as Shaurdoril of Wolgommen -- by sanctifying a silver ballista bolt and commanding the soldiers to aim it at Veriviet's great gem embedded in his chest armour. Veriviet's great sword, Miesich, remains at the sight of his death to this day, standing upright like a narrow tower leaning before its collapse. As the land itself kills any who step upon it, the sword can only be seen from a distance, and even then at risk to the viewer.
Though records vary, many witnessed a colossal magical creature, as stated. It had the rough form of a black whale covered in mountainous spikes and was constantly wreathed in turbulent clouds and electric storms. The entity itself was allegedly 2-5km long (1.2-3.1 miles), so vast that if it ascended or descended it would create hurricane winds that could tear trees out of the ground, and could unload a smaller storm of any combination of ferocious winds, lightning, or fire at will. The Antemplars, an ancient order headed by demigods with several cults of humans trying to earn their favour, have claimed responsibility for the attack, making them one of the most feared orders of beings in Riiga.
Across northern Baracsa, and western and central Armalia -- the main areas to have suffered The Darkness -- there are storms which are believed to be remnants of the Darkness which occur approximately once every 50-100 years. These events are called Black Storms, Dark Tempests, or similar, and are different to a regular storm due to a few distinct features.
Firstly, Black Storms are preceded by a more profound environmental change than regular storms: clouds that gather are especially turbulent and dark, a rumbling can be felt from it, and some people in the area may feel a certain dry or tingling sensation. A rare type of bird called the synavos is especially sensitive to these changes, and emits a mournful cry when it does, noticeable due to its normally quiet demeanor. Synavos are usually kept in large cities in a specific tower called a Crying Tower, found on only the largest of castles or palaces. The cry is passed on by means of giant bells, horns, drums, or lines of beacons. Antemplars are known to hunt these birds to reduce the effectiveness of civilised warning systems.
Secondly, the storm brings a darkness as deep as night, lightning which is dark purple in colour, thunder that sounds more like tearing of the air rather than explosions, strong winds, hordes of monsters, and sometimes rain. If the storms are anywhere near civilised areas, humans muster forces as quickly as they can, expecting a monster attack. Indeed, most Black Storms bring monster invasions, though some do not. These storms tend to last anywhere from two to seven days, and will move very slowly across a landscape. Sometimes they seem to change direction. Some claim to have seen Murluron himself in the tumbling clouds of Black Storms, but no historian or priest has ever managed to verify such a claim.
Thirdly, remnants of the storm include a type of stone left over from when the purple lightning strikes certain types of ground. A rare crystalline material called aetherite is formed in this way, though most of it was formed during The Darkness, as the lightning in modern Black Storms is nowhere near the power and intensity of the lightning back then. Aetherite is a very potent carrier of aether, and can theoretically be used to amplify magic by using it as a vessel, material, or container, though this is yet to be achieved by anyone. Aetherite exposure corrupts the wielder rapidly: signs of corruption include a purple-black powdery look to parts of the body nearest to the aetherite, and around the orifices of the body; a gradual detachment from reality and inability to maintain coherent conversations; a drastic loss in mental and physical capability; and a tendency to experience hallucinations of a sinister nature. Despite Black Storms occurring at least once every several decades, aetherite in any substantial quality is extremely rare and extremely dangerous. Regardless, it is contraband in all major human civilisations that know of its existence.