Alright, I warned for spoilers. So here we go...

This is honestly very simply feedback, but I would just like to be able to "fix" the moon up a bit. That is, be able to perhaps "fill in" that massive, gaping hole in the middle of the zone.

My personal suggestion?

Replace it with a "biome" of some kind, with a garden in the center. Perhaps created by the Loporitts, or perhaps by Hydaelyn, Meteion, or even an uncorrupted Zodiark.

That last one may seem a bit of a stretch, but actually I think is the most compelling. Maybe we finally "meet" the remnants of Zodiark, that much like Hydaelyn represents a kind, nurturing mother, Zodiark is more of a "stern, protective father", who believed the inhabitants of the Ancients' world were too weak to stand a chance against the End of Days. Content to see you've proven yourself capable of confronting the threat head-on, he hopes you will continue to grow into a warrior of even greater, cosmic power.

Perhaps recognizing Hydaelyn's power is effectively spent, in recognition of her as an equal, he creates a garden in place of his shattered prison, that her soul might find rest looking out over the world she fought to save. Maybe even hint that Meteion's spirit might come to rest there, as well.

Heck, maybe there's even some tiny reservoir of aether left there, that they still "live" as spirits, but no longer with the power to actively aid us anymore? Or it can just bring a sense of closure to their stories.

Either way, I just feel like the Moon SHOULD be a really cool place, but that gaping hole filled with evil-looking energy just kinda kills the vibe.