It all began with dreams.
At first it was just dreams of fire, of bright lights followed by darkness. Then it was dreams of screams, of terror, feelings of loss and entrapment, of peril and pain. The thing was, EVERYONE had the dreams. Even the elves, who sleep only rarely and never for long, had the dreams.
Then came the sound. Every day, a long drawn out keening sound, as if the sky was being rent in twain. It happened at the same time, everywhere, echoing from here and there.
Then came the dragons. Flights of dragons, all converging in the sky to talk. Deadly enemies, longtime foes, all came to speak on the omens it portended.
Last came the rips, tears in space that vomited forth strange creatures and strange men who spoke of other worlds and other places, of things that had never been and places that no longer existed: of Azlant Victorious, of the flying cities of Garund, of the lost city of Absolom, or the Disappearing Trails of Old Cheliax. Of cataclysms, catastrophes and things even worse.
The world began to buzz with talk of the ending of this age and whether a new one would arise. The fey began to speak of the Third World, a refuge to flee to when this world was no more. In the midst of all this talk, a meeting was convened by a little old man who called himself Prester Gallowsmith. You've been a message, delivered by a thrush, that invites you to come to Absolom, to the home of Prester Gallowsmith in one month's time to discuss the end of the world. The letter is signed with a signature and a sigil: three interlocking circles with a spiral at the center. It's not a symbol you're familiar with, but it seems to evoke a sense of familiarity none the less.
Against your doubts, or perhaps because of them, you've decided to attend. You choose your travel methods carefully, but you know that you may never pass this way again.
In the year 4712, in the Age of Lost Omens, on the leapday of 32 Arodus, a gathering was held in the home of Prester Gallowsmith in the city of Absalom. It was attended by men and women of all races, of all walks of life, with no particular connection. It begin with an argument and ended with the everything changed. It began a new age. - Book of Endings, author unknown
Prester Gallowsmith: "I am a member of a brotherhood of men who study the planes and the stars and the space between. For many years we have met quietly to share our insights and to speak of the knowledge that we have gathered. The death of Aroden changed everything. Suddenly all the omens and prophecies ceased to function, and even basic divinations could not be trusted. It was in that moment that a brother of mine observed a strange occurence heretoforth unknown to us. During a simple teleportation effect, he observed that the Golarion of his destination was not the Golarion of his departure. Fortunately he was not stranded on that strange shore and was able to return to us with his findings. From that moment, we were able to make several discoveries. Bear with me; the path ahead is not a clean one."
He pauses, gathering his thoughts. "We have discerned that every major event in the history of our world holds a certain temporal energy. It permeates the planar boundaries and as we found out, alters them. You see, every major event or keystone moment creates a potential for an equal and opposite outcome. The very energy that causes history to hinge upon that moment creates its opposition. When this occurs, a new Golarion is produced, divergent from our Golarion in that moment. If the event is strong enough, that Golarion continues, evolving in its new path separate from our path, spawning its own alternates. If it is weak, it will die, usually within a few days, but we have seen such realities persist for longer before fading. Indeed, in Pharasma's Boneyard, there may well be a graveyard of such realities. But I digress. In this garden of forking paths, there is a always a prime path, a Golarion from which all others sprang. Our world is that world. However, it seems as if the weight of these other realities is becoming too much for this world to bear. The rifts are the result of this stress. They are the tears where one reality intersects with another, and if they are allowed to continue, they will eventually cause all realities to collapse in upon each other, destroying them all. We know not why or where this threat comes from, but we believe we may have a way to stop the collapse."
Gallowsmith pauses and the mosaic tiles composing him rearrange to form a sort of network of roots. "In each reality, we have identified a keystone, a place or person or thing upon which that reality rests. These things have become lacking in some way and must be rectified if that reality is to be shored up against the collapse."