I. I just spent an entire commute contemplating how to naturally segue them from battle for bermesiah into xenia because the current dialogue is batshit insane and doesn't make any sense!! Tbf even pre major retcon (putting silver land before ellia, which was a bad move, by the way!!) bfb dialogue didn't really make much sense, so. I. I connected all of the dots. I connected dots that didnt even exist and im honestly so impressed with myself

1. While in ellia, they get a telepathic message from lenasien, like in canon, but THIS time, he tells them that an oracle has prophesized that the grand chase's homeland is in danger from dark anmon, and that he is telling them this in the hopes that they will return the favor by coming to their aid in xenia afterwards. Said oracle is, of course, amy, and she foretells that they are the only ones who can save xenia from the growing darkness.
2. They do, in fact, as the NAME IMPLIES, travel back to berm (what the heck were they doing retconning this out????)

2 cont. They travel back through bermesiah to defeat him and his now explicitly necromantic army, since I think that's the implication for the orc lord and fairy queen coming back.
3. To fulfill their end of the promise, they need to find a way to xenia. Well, Jin, as a silver land knight (the only one left...) knows that the oracle (amy) once was able to travel from silver land to xenia, so he suggests that they return there to see if they can find a way (and indeed, a portal has opened up courtesy of lenasien and amy) this answers the question of how in the world they managed to get to a floating island since I'm very doubtful they have the technology for airships in bermesiah. Additionally, Jin can suggest that they ask Amy about traces of Kaze'aze, since they're still looking for her and have no other leads

I... I had to figure this out for my fic LMAO but I think this will just permanently be part of my internal gc canon from now on. I really wish they hadn't so drastically changed the plot with their revisions over the years, though I admit that it was never clear how they got to xenia or why lenasien would contact them, a gaggle of teenagers, to come and save literal gods. But prophecies, amirite?

Oh, and dark anmon has nothing to do with xenia and shouldn't even mention anything about it; like ryan said, he was a fallen druid, and now that Kaze is gone, he wants to subjugate the continent instead. Just a relatively normal evil motivation. Delete the weird implications about xenian dark energy flowing into bermesiah, it's unnecessary and doesn't make any sense.