From the reader's point of view, Caliborn's story in The Homestuck Epilogues picks up from where his Canon biography ended.
Caliborn appears only briefly in The Homestuck Epilogues, wherein we get a more direct look at the events of A6A6A5. The older John who had zapped back into canon from the epilogues, along with the seven teenage versions of the god tier kids he brought with him, initially find themselves in a dark void. Jade quickly locates Caliborn in this abstract space, underneath a gray spotlight, dancing with Lil Cal. Gamzee and Seb, naturally, are also present.
After some initial confusion, Caliborn recognizes John, and begins to ramble about the claymation reenactment of the very fight that's about to take place. Much time appears to have passed since Caliborn's appearance in Act 7, as he refers to the claymation as “THE MASTERPIECE I MADE. WHEN I WAS BUT A BOY.” He brags about it at length, laughing the whole time, as his jaw unhinges and his voice distorts. John and the others soon engage in a fight with Caliborn, which the narration seems to indicate was much less one-sided than the initial claymation implied. Caliborn eventually feels overwhelmed by the fight, and he decides to finally unleash the Juju on the four beta kids. They all get sucked into it almost instantaneously, and Caliborn laughs at them as he returns the Juju to the chest and closes it.