The party has finally met its match.
As the party tries to rest and regroup in the courtyard of the flying castle, they see the tear between the planes open up again - and monstrosities flow through. From down the staircase comes a roiling chaotic blob dissolving everything in its path. The party, in its injured state, runs wisely but as soon as the monster appeared, it was gone and the world was right again.
The party decides to continue up the stairs with the goal of the control room at the top of the castle. Niko peeks under the doors as they go and triggers a chaotic evil love monster, intent on impregnating Niko or anyone. The party once again flees toward the top, but the eye-tongue creature follows, changing shape to gain speed as it goes. Brennan's flying saved the party again.
The party eventually becomes trapped between the love machine and a swarm of mind affecting dandelion fluff. A fireball ignites the entire area, taking care of the fluff, and the PC's eventually defeat the love machine, but not before Gaius was covered in its juices.
At the top, the pc's find the lost Kyne, floating and glowing again. He seems drawn toward the rift outside and dissolves the giant door in his quest to return the "Other" to its own world.
Here at the top is the control dome and the party rushes in to deal with the masters of the castle. Once inside they find themselves facing insurmountable odds. An Oni samurai, a cloud Giant monk and many pole arm wielding giants. In the room is also Lady Thrune working the device that is controlling the rift.
After a short debate, the PC's jump to action and Aether drops the rift machine into a pit - not realizing that the machine also controlled the flying castle. As the castle tumbled from the sky on its way to the vast ocean below, the party engages in a losing battle, in a falling castle, against fresh and overpowered enemies. The floors become ceiling, the walls become floors as the castle topples away.
Niko is defeated by the Monk Queen, and Kyne is next to fall. Kyne's flesh falls from his body and the "Other" is freed. Brennan is hurt badly and tries to save Lady Thrune who said she could regain control of the castle. She couldn't in time. Brennan escorts her outside and is left floating in the sea hundreds of miles from land.
Inside, Aether and Gaius try to finish the job of killing the monk and samurai but time ran out. Seconds before the castle hits the ocean they dimension door out. But the chaos of the planar rift sends them to the plane of Shadow.
Their bodies still inside the castle Kyne and Niko and the castle disappear inches from the ocean as "Other" successfully opens a gate to his plane and takes the entire castle with them.
Floating in the ocean with Lady Thrune, Brennan once again sees Golarion fall into chaos and maybe destroyed for good.
The Plane of Shadow, sapping the life and minds of Aether and Gaius was not very hospitable. In their instant fortress Aether calls upon the magic of Servino's paint set to paint a portal to the bridge of the airship they lost contact with. As they step through, they come face to face with the Mordant Spire elves they had defeated only days ago. The elven mage, druid and whole crew stand face to face with a battered and drained Gaius and Aether as they await their fate at the hands of their bitter enemies.
The castle is lost, Kyle is lost, the core and amulets and ship is lost, the party is split upon numerous planes and the world is in literal chaos. There is not much hope right now. As Aether and Gaius plan on going out in a blaze of glory the only questions that remains is...
What is our xp for the last session?
The players will have to decide how the story continues. Not everyone is gone, but we have Thorac's story arc or possibly a new game also to consider. How will the Castle at the Edge of the World end - with a glorious battle against Nyrissa's army or with the choices of the player's pasts finally catching up with them?