A Confluence (also referred to as a Convergence) is when a Tearworld's orbit
leads it into the shell of Arkath's Divide, and in doing so weakens the
Veil and the Weave. As a result that Tearworld momentarily merges with
the Core Planes, allowing inhabitants and energies of that Tearworld, the Planeworlds and the
Core Planes to enter into each other with greater ease.
Confluences are rare and
typically one only occurs once in many thousands of years. Each
Confluence is also brief, but has lasting effects especially on Nym;
normally by stranding an Otherworld race in the Core Planes, or by
causing unnatural damage in a region, or affect Nym on a grander scale. A
Confluence destabilizes the natural and arcane laws of the world, and
as a result creates visible chaos throughout the Core Planes' physical and immaterial structure. Typically
these effects die down after the Confluence passes, but lasting
effects can linger afterwards.
There have so far been six notable Confluences that have occurred in our world. It is very likely that future Confluences will happen as the other Tearworlds inevitably near and pass into the Core Planes, though it is almost entirely impossible to predict such events before it is too late. Astronomers try to pierce and study beyond the Veil in an attempt to observe the Tearworlds and their trajectory, but at most they are only able to perceive that the Tearworlds are there, and not their likelihood of starting another Confluence.
THE FIRST CONFLUENCE - SAN-KA:
Said to have occurred some 23,000 years ago, the Confluence of San-Ka was unprepared for its merging with the Core Planes, as the Weave and Veil hadn't yet been formed to properly alleviate the unstable energies of two worlds merging.
The powerful energies that clashed as it merged with the planet Nym tore San-Ka apart; shattering it into several pieces. On the planet Nym, the destabilized energies caused surges of unleashed energy to disturb the fabrics of the spirits, and many began to disappear or dissolve.
It was at this time that the Kal'Mar vanished from the world, and it wouldn't reappear until several thousands of years later; after the Worldblight occurred and Malendii brought the Kal'Mar back from where it had slumbered.
San-Ka itself still exists, although it is no longer a whole world. Its floating rocks and broken lands are anchored to the Tearworld's core, and its inhabitants have adapted and learned to survive; creating a society of world-travellers who can jump between worlds on specially made vessels. By visiting other worlds, they bring back various resources from those worlds, so that those on San-Ka can continue to survive.
THE SECOND CONFLUENCE - AR-ZHALA:
At the end of the Time of Stars (roughly 10,300 years ago), the Confluence of Ar-Zhala merged with the planet Nym, and sucked in vast amounts of still untamed void energies; that had been created from the War of Stars, as well as the negligence of Tiral's Tidewoven children, the Maaré and Maéc.
As it consumed the void energies for itself, Ar-Zhala's and Nym's energies created a sudden surge that managed to shatter the Dragonsoul; awakening the dragons. It was through the shattering of the Dragonsoul that the Elder Dragons returned, and, in witnessing the past destruction brought on the world they had once shaped, some of them defiantly became the Dragon Gods, and heralded the beginning of the Second Era.
Ar-Zhala's consumption of the void energies effectively managed to clean the planet Nym of its tainted magic; something Tiral had attempted to do before, but was unable to do so because of her Tidewoven children's actions. But because Ar-Zhala took in all those void energies, it became a Tearworld of highly arcane and unstable magic, and Tiral still visits it to siphon some of its void energies into her Planar Seas.
THE THIRD CONFLUENCE - SYL:
At the height of the Wyld Ages (ca. 8000 years ago), Malendii's Wyldtrees (created for the purposes of absorbing blight energies caused by the Worldblight) would be affected by the Confluence of Syl. Spores, seeds and other sentient, wild plants from Syl fell to the planet Nym as Syl merged with it, and many of these would become afflicted with blight energies. Some seeds corrupted a number of Wyldtrees; spreading blight instead of absorbing and containing it.
Some of the creatures from Syl, unafflicted by blight energies, would remain hidden in the world or join Malendii's Dreampact. Those who joined the Dreampact became the dryads, naiads, fairies, and other similar feykind, and as allies of Malendii, they would try to protect the remaining Wyldrees from corruption.
It was only after the Confluence of Syl that Malendii started having nightmares, and the Nightsoul was created in her Sleeping World. Phantasms, nightwraiths, and other nightmare manifestations would begin to appear in Malendii's Dream and in the Waking World of Nym.
On Nym itself, the various wild seeds have grown and spread within the jungles and forests of the world; most being dormant until potential prey stumbles across them.
THE FOURTH CONFLUENCE - IBEL'ACH:
Not long after the Confluence of Syl, the Confluence of Ibel'Ach occurred some 700 years later. At first its effects were minor; creating a seemingly eternal night that wouldn't return to normal until a few days later. But as more time passed, the effects of the Confluence of Ibel'Ach became more apparent.
100 years after the Confluence, the sarazhi kingdoms started to disappear; their people answering what they referred to as the "Deep Call" as they moved deeper towards the Abyssal Depths. In the Underneaths, sectizh descendant (the Creator Signis' elevated Arachnyr servants, as well as the independent Vithrid), fled to the surface, speaking of a darkness forming in the Deepdark. Even goblins and the previously hiding trolls surfaced from the Underneaths.
It wouldn't be until a lot later that the true cause would be discovered. Eldritch, originally from Ibel'Ach, had implanted themselves within the Underneaths, and had conquered the deepest realms. They became Eldritch Gods, and have since remained in the darkness of Nym's Underground Realms; possibly building strength so that they can properly enter the surface world.
It was also only after the Confluence of Ibel'Ach that rifts leading to Riftworlds began to appear throughout the various and distant lands of Nym; usually in areas where unstable arcane energies are strong.
THE FIFTH CONFLUENCE - NAGAL'OR:
2900 years ago, around the time of the founding of the first Celestial Dynastic Empire of Canthar, the Confluence of Nagal'or occurred. A great sickness, named the "Necrotic Plague", swept across the entire world and killed thousands of its inhabitants; leaving entire civilizations lifeless. Most civilizations would eventually recover later; having either endured or been repopulated by a different culture.
As a Tearworld of necrotic energies, Nagal'or's merging with Nym resulted in an increase in necrotic and necromantic creatures. Mainly it was the integration of three necrotic races that stuck out at the time; the vampiric Vrayth, the beastly Ghûls, and the ethereal Liches.
Most of these beings would appear in Ryumar, but various sightings and confirmed communities of Vrayth, Ghûls and Liches also appeared in Korash, Ashanor, and Aesudarh. Because of their arrival in Nym, the number of creatures created from undeath and necrotic energies vastly increased; leading to several civilizations at the time to either embrace them, be consumed by them, or actively fight against them.
It is said that a part of the Necrotic Soul, which is mainly trapped within Nagal'or, was left behind on Nym, which is why necromancers and other practitioners of necrotic energies became stronger and more common throughout the world. Those who make use of necrotic energies would, after the Confluence, find it easier to establish a connection to the Tearworld of Nagal'or.
THE SIXTH CONFLUENCE - TAL TOREN:
Around the time of the Old Imperium's rise, some 1700 years ago, the Confluence of Tal Toren sent large chunks of that Tearworld crashing into the various lands of Nym. These meteoric storms caused great destruction especially in Ryumar and Korash; leading to the fall of several ogre kingdoms in Korash, but strengthened surviving kingdoms.
These meteors carried with them stones of neutral energies that spread to several spiritually strong aethra stones and minerals around the world; converting and transforming them into the energy- and magic-neutral mineral of Duraritium. This mineral is considered highly valuable because of its high tolerance for magical energies, as well as for its value as a strong, durable metal.
Supposedly dwarves started becoming more magically resistant after the Confluence of Tal Toren, which might also explain why the dwarves can't seem to use magic very well, or why dwarves very rarely experience Magical Awakening. The actual specifics as to how or why this happened is still largely a mystery.
The meteors didn't only bring with them Duraritium, but also several Torians who became stranded in our world. The various Torian tribes have since spread into various regions of Ryumar, Ashanor and Korash; creating smaller, isolated societies where they have continued their old way of life from Tal Toren.