Planar Instability

Planar instability occurs at a point where the "membranes" between realities has grown thin. The boundaries between planes collapses inwards into a magical singularity that punches a hole in space, and possibly time. The phenomenon is well known throughout the multiverse: portals in the backs of wardrobes, magical rabbit holes, and stargates in the void are all common examples of this same instability. The Kirinal Pit, a thirty-mile-wide wound in the world of Erathia, is among the largest and most stable known cases.

The instability, unleashed at the end of the Lichwars by the Kirinal Disintegration, causes the Pit to Manifest fragments of other planes or worlds at random intervals. Left unchecked, the Pit would continue to expand, devouring the world piece by piece, and flinging its remnants out into the multiverse.

The Navigator of Worlds, Chagroth Durinhelm, arrived at the Pit shortly after its creation. Already a mighty wizard, he dedicated his life to stabilizing the rift. Over decades, he constructed the Orrery of Worlds and devised the weekly cycle that now defines life in the Kirinal Concordance Zone.

The system of fortresses and armies around the Pit was established to contain interdimensional incursions and prevent invasions from spilling out into the wider world. The Embassy Cities were later founded to support the fortresses and the soldiers who manned them.

For decades, people shunned the Pit and the cursed lands around it. They were terrified of the horrors that crawled out of it and haunted the Kirinal Wastes. When the Kirinalos discovered the riches of the Manifest, harvesting resources and trading with its denizens, settlers and fortune-seekers began to flock to the Pit, eager to claim their share of its bounty.