Spellplague

The Spellplague, called the Blue Breath of Change by the inhabitants of Abeir, was a disaster that struck Realmspace and even the planes themselves on the date of Tarsakh 29 in the, and was caused by Mystra's assassination at the hands of Cyric and Shar. It continued for a decade, leading to the Wailing Years, during which arcane magic ceased to function and the planet of Toril was transformed.

The diviner Yaphyll had a vision of the event: ""The white queen is troubled but can't say why. The black queen hates the white and gives the assassin a black coat. The assassin steals upon the white queen. She can't see him gliding through the shadows. The sword screams. The white queen falls. Her city falls. Stones fall in the cavern to crush the soothsayer. The tree burns and thrashes in agony. Branches break. Branches twist and grow together...""

- from a vision by the diviner Yaphyll

In her vision, Yaphyll referred to Mystra as the white queen and to Shar, goddess of the night, as the black queen. Cyric, god of murder, was the assassin; Savras, the god of divination, was the soothsayer,, and the city, cavern and tree symbolized the ordered structures of magic crumbling into chaos.

Origins
The most popular and widely accepted theory about the origins of the Spellplague was that this calamity was caused by the death of Mystra, the goddess of Magic. For eons, magic had been bound within Mystra's Weave, the universal structure of arcane forces, and her death tore the Weave apart and unleashed the raw magic contained within it, creating the cataclysm that was later known as the Spellplague.

Other scholars, however, didn't consider this to be a logical explanation. Historically, two earlier incarnations of Mystra had died before only to be reborn, and the Weave maintained its hold over the power of magic for the duration of her deaths. In these scholars' views, the truth would never be fully known to mortals, and perhaps not even to the gods.

Around 1396 DR, the sentient construct Cynosure theorized that the escape of an entity named the Traitor from its confinement in the dungeons of Stardeep, around the same time Mystra was murdered, may have also influenced the Spellplague's virulent onslaught.

The Plague
Mystra's death caused the Weave to collapse and, without the Weave, the Shadow Weave was unable to be maintained and collapsed as well. The breakdown of the Weave was felt by all wizards across Faerûn. The corrupted madness of Cyric defiled what arcane forces remained from the dissolution of the Weave, resulting in a new magical source of defiling arcane energy in the form of blue flames that destroyed Dweomerheart and continued to spread across the multiverse.

Creatures and individuals who came into contact with the Spellplague risked being killed or being warped by its energies, in which case they were said to be "plaguechanged". This entailed massive physical mutations and often a complete loss of sanity, and sometimes bestowed the creature or individual with terrible powers. Those who came into contact with weaker versions of the Spellplague were sometimes lucky enough to escape with only a spellscar, which could also bestow potent magical abilities.

The Storm of Blue Fire
The Spellplague manifested in Toril as a storm of blue flames in the Mhair Jungles, west of Halruaa, and quickly grew to a massive size. Halruaan wizards, having divined the death of Mystra and the destruction of the Weave, were able to use the energy of the blue fire to save most of their kingdom by shifting it into another world, Abeir. However, the remaining Halruaan lands in Toril were laid to waste due to the heavy wild magic activity in the area, in such a catastrophic way that the explosion was felt as far as Waterdeep. Sespech, the Golden Plains, and the Nagalands were also affected, and those lands were transformed into an unpredictable and surreal place, dubbed the Plaguewrought Lands.

The blue flames also infected portals and planar gates, spreading even further across Toril. Almost every part of Faerûn was affected by the Spellplague and certain areas were eliminated entirely, while others were created anew. Thousands of spellcasters were either destroyed or went insane due to the collapse of the Weave after Mystra's death. In Cormyr, a third of the War Wizards were either killed or driven mad. Those who survived lost their ability to use arcane magic.

It was through the planar gates that the Spellplague traveled across time and space, and reached the world of Abeir. In that world, the Spellplague first appeared in Gontal, the southwestern region of the continent of Laerakond, where it made contact with ancient Glaur, the fortress of the Primordial Nehushta. The fortress detonated when the "Blue Breath of Change" ran through it, in an explosion as potent as the Tearfall, rocking the entire planet of Abeir and creating the Glaur Barrens where the old fortress once stood. Laerakond was torn apart in a powerful earthquake, and a portion of the nation of Skelkor, where the capital of the dragonborn nation of Tymanchebar was located, was torn asunder and disappeared amid the blue fire.

That region, where the city-citadel of Djerad Thymar was located, crashed on Unther, still enveloped in the blue flames. Many believed the Untherites and the Mulhorandi occupation forces were obliterated in the explosion that leveled and reshaped the whole region except for the Black Ash Plain, but actually Unther was instead transported to the world of Abeir. However, it was transported to the lands of Shyr, the equivalent continent to Faerûn in Abeir.

The rest of Laerakond was sent to the Trackless Sea, where it subsumed the lands of Maztica. Maztica was transported to Abeir, and Laerakond, which became known as 'Returned Abeir', remained on Toril.

Effects on arcane magic

 * Despite efforts, with the structure of magic out of balance, many spells failed or produced unreliable results.
 * The Wards of Silverymoon were shattered.

Effects on the Gods

 * Savras died as a result of the dissolution of Mystra's home plane, Dweomerheart.
 * Azuth was thrown from Dweomerheart to the Nine Hells, where Asmodeus stole his divine essence, fused with Azuth, and became a god.
 * Cyric was tried by a conclave formed of Lathander, Sune, and Tyr. They found him guilty of Mystra's murder and sentenced him to imprisonment in the Supreme Throne.
 * Lathander transformed back into Amaunator.
 * Nobanion tried to save a pride of lions in Gulthandor from oncoming blue fire. He came in contact with the blue fire, and it mutated him into a dark and bestial lion with a mane of blue flame.

Effects on the planes

 * The World Tree was destroyed.
 * Most of the Outer Planes were either destroyed or merged with others, creating the Astral dominions. Entirely new Astral dominions also arose because of the Spellplague.
 * Dweomerheart itself was dissolved.
 * The Spellplague pulled back the Feywild into Toril's proximity, reopening the paths between the two planes again.
 * With his newfound godly power, Asmodeus took advantage of the planar instability to hurl the Abyss to the Elemental Chaos in an attempt to end the Blood War. Asmodeus failed, however, as throwing the Abyss into the Chaos did not stop the Blood War, although it was stalled by a hundred years.

Other effects

 * The Spellplague affected the landscape, making the ground rumble and heave up and down like the surface of the sea. Curtains of blue flame swept the landscape, reshaping the land by cutting crevasses or lifting and sculpting the plain into hills and ridges. Shards of earth wrenched themselves free and became earthmotes.
 * Waves of azure fires appeared everywhere, killing whatever they touched.
 * Rifts opened in the Underdark beneath the Sea of Fallen Stars, causing the level of water to drop, cutting many ports off from their livelihood and creating the Underchasm.
 * Humans that were somehow tied to the Shadowfell were affected by the Spellplague and transformed into a "new race", the shadar-kai.
 * Southeast Chessenta was also obliterated by the creation of the Underchasm. Chessenta survived and prospered - though its beloved ruler Tchazzar disappeared without a trace.
 * Mulhorand was completely destroyed, and the Mulhorandi pantheon disappeared. The land was later settled by Deep Imaskari and became the empire of High Imaskar.
 * Chult became a large island when most of the Chultan Peninsula was cut off from the mainland. Much of Samarach was drowned, its survivors spellscarred, and the yuan-ti realm of Serpentes fell. To save the city of Mezro from destruction, Ubtao's barae created a demiplane and transported their city and all its citizens there. They left behind artificial ruins occupied by undead to discourage people to find what really happened to Mezro. According to the bara Alisanda Rayburton and the naga Saja N'baza, Mezro would not return to Toril as for as long Ras Nsi was alive. Likewise, the Chultan jungle became home to massive monsters from Abeir.
 * The peninsula known as Var the Golden became a region of the Great Sea called Var the Drowned.
 * The Misty Vale was destroyed by changes in climate, though the wild elves that occupied it survived. Known as Elfharrow, it was fiercely defended from all intrusions.
 * The Shaar became a wasteland called the Shaar Desolation.
 * The region surrounding the Great Rift became the Underchasm. Bits of what used to be the Underdark began to float above the Underchasm as earthmotes.
 * The halfling realm of Luiren was submerged underwater, becoming the Gulf of Luiren in the Great Sea. In the century since that great disaster, the waters receded, and stories told by travelers from the south told of halfling communities that survived as island redoubts.
 * The sudden shifting of continental bodies sent tsunamis all along the island and coastal regions of Faerûn, devastating them all. Lantan was hit harder than most. Before the waves reached the island, all the smokepowder and magical reagents exploded at the same time, causing great chaos. And as the waves reached the coastline, most of Lantan was engulfed by the blue fire and send to Abeir. What remained of Lantan on Toril was entirely flooded, killing the remaining Lantanese and cleaning away their advanced technology.
 * Evermeet was pushed into the plane of Faerie, leaving behind a pale shadow of what the island of the elves used to be, though the isle's residents could move back and forth from Faerie to Faerûn at will.
 * The island of Nimbral suddenly and mysteriously disappeared.
 * The illusions that cloaked the settlements on Selûne failed, revealing them to those on Toril.
 * In Neverwinter, although the city was not as hard hit by the Spellplague like other places, its effects were also felt. Some buildings were affected by the aberrant magic, such as Castle Never, the Cloaktower (that was sent to the Far Realm ), and the Fallen Tower, Chunks of earth near and in the Neverwinter's Docks District became earthmotes, including the land on which the Moonstone Mask was built. Also, a small plagueland was formed in the Underdark below Neverwinter.
 * In Waterdeep, the Walking Statues of Waterdeep (most resided in the Ethereal Plane) appeared in the city and began to rampage. The Blackstaff at the time was unable to control them or banish them back to the Ethereal Plane.
 * Parts of Conyberry were exchanged with lands from Abeir. The Abeirans survivors were soon accepted by the citizens of Conyberry, and Conyberry became a prosperous village, at least for a time.
 * The Tower of Twilight, hit by the azure flames, was expelled from the normal timeline and vanished from reality. It did not return to Faerûn until after the eruption of Mount Hotenow, in 1451 DR.
 * In 1386 DR large parts of Abeir and Toril switched places (small, almost imperceptible parts had been switching places since the Time of Troubles but this event was markedly more noticeable). A portion of Shyr violently changed places with large sections of Chondath and western Chessenta. Displaced genasi quickly set about creating a kingdom of their own, Akanûl.
 * Political upheaval across the land that resulted in many attempted coups, invasions, and uprisings. Especially against governments and nations that had relied heavily on arcane magic for defense or controlling their population.
 * The number of people gifted with psionics increased exponentially in Toril ever since after the Spellplague. Some scholars believed this was a reaction against the Far Realm-defiling energy of the Spellplague.
 * In Leilon, the monsters that were forced to guard the High Tower of Thalivar and its secrets were released from their bonds to terrorize the city. The magic inside was redirected outward into the town, paralyzing anyone who gazed at it where they stood.

Aftermath
By 1395 DR, the majority of the effects of the Spellplague had come to an end and most arcane magic had returned to a semblance of normality, with a handful of major changes to the way spells are cast. The Empire of Netheril came across the Lost Vale and displaced the saurials there into the Underdark.

By 1479 DR, areas of Toril still affected by the Spellplague were referred to as Plaguelands. In Neverwinter, victims of the Spellplague were expelled from the city to live in Helm's Hold, where those with severe mental or physical afflictions were sequestered in a terrible Sanatorium.

By 1480 DR, the Spellplague had ended with the event known as Mystra's Return. The Weave was resurrected with the goddess and magic became what it was before the Spellplague, though some areas with lingering effects from it remained.

In 1482 DR Lord Ao began the Second Sundering, as a way to restore the worlds of Toril and Abeir of the ravages of the Spellplague.

Connections
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