The Cataclysm

The Cataclysm, or Karithat-Aldawi in Khar-Kushak is the singular most pivotal and also the least understood event to ever happen on Dunia. The initial flash of light that occurred erupted from the tallest mountain in the Vertebra, Mt. Aarahat, destroying it and roughly 2,000 miles of the surrounding mountain range, sending debris in all directions. The initial energy burst left a crater in the center, radiating outwards. What people do know with certainty is only what it caused.
The first shockwave traveled outwards at an elevation of roughly 3,000-8,000 feet, dampened somewhat by the surrounding mountain ranges, sparing some areas from the initial burst of magical energies that evaporated a good measure of the water in the surrounding land and killed incalculable amounts of life in an instant. This first shockwave toppled the tallest buildings in Khadiba-Maksur, sending debris cascading downwards and crushing people below and in the surrounding area. Its upwards eruption reached out to space and destroyed the orbiting satellites in position above the Aarahat region, creating a cascading effect of high velocity space debris which destroyed other satellites, knocking out most satellite-bsaed communications in a matter of minutes.
The second shockwave came only a short time after, with less directly forceful energy but it still destabilized the ambient magical particulate in the atmosphere, causing a fallout-like effect that also intersected the planes of existence with others, pulling peoples and animals alike to Dunia. This was carried by air currents in the stratosphere to other corners of the world and occurred at a much higher altitude. The effects of this were not understood until small flecks of magically-charged dust started settling and drifting downwards. Upon settling on some of the plants and animals, it mutated them in unpredictable manners and yet only selectively. It contaminated the streams with magical particulate and altered the life in the waters, too.
The ensuing chaos disrupted all facets of life, manifesting in ecological disaster and dissolution of nations. It was an uneven and inequitable apocalypse, uncaring and unaware of all of the anguish it had unleashed upon the world; after all, it was entropy's manifestation. Droughts caused mass die-offs in both animal and sapient populations. The rate of habitat loss was incredibly high, and very few were spared the worst of it. All in all, it was estimated that anywhere between 40-80% of the world's population was lost either to the direct effects of the Cataclysm or its residual fallout.
The full extent of the Cataclysm was only beginning to be understood. Life on Dunia was forever altered. Nothing would remain the same from then on.