[MAJOR ENDWALKER/SHADOWBRINGER SPOILERS] On the introduction of dynamis.

[Loggos]

The answer also was for OP, but it did drift on yours ahah

Oh oops, I'm sorry, haha!

As for Meteion, I think that's why she *has* Aether : she was created as an aetherial being, with very little aether though, and in away to make her as attuned to Dynamis as possible. She's not literally made of it though, or at least a "proto meteion" isn't created with Dynamis, but she does use its energy on a day to day basis.
As Hermes said, just not having aether isn't enough to be an entelechy, so it probably took a lot of trial and error to get there. He kinda had the Elpis flower to retroengineer.

Ah this makes a lot more sense. Then this means that Hermens didn't use Dynamis directly to create Meteion but constructed her in a way based on aetherial principles that would make her own ability to manipulate it possible.


(And now that I think more about it, I remember the reason for the magical beings in Amaurot turning into monsters was their low aether density.

So iirc it's not the Ascians' magic itself that was influenced by Dynamis.
They probably didn't accidentally manipulate it when creating something.

It was most likely the result of that magic, i.e., the beings which have some form of sentience and some sense of emotions (but perhaps not a soul), as stated by Hermes who told us creations were full of fear or rage when they were about to be killed.

So I guess these beings were able to feel some form of despair themselves that Dynamis could have reacted to - maybe because there were to be killed by Ascians.

Or maybe because being part of the natural food chain (in Elpis or after being released on the planet) causes despair. If you are about to be eaten by a predator in the wild then that fight for survival and the terror of dying, or the pain while being devoured (some animals eat their prey alive after all) could trigger the transformation of these creations.
From there on the chain reaction could have been set in motion because if suddenly gangs of super predators suddenly raid the planet then I can imagine that this naturally causes great fear in animals, esp. prey animals, and you can't just tell them to "control" it. This could also explain why Amaurot, being a big city removed from most mortal life and not "the wild", was hit last.

This kind of makes sense to me. But now I wonder why animals in Eorzea did not transform during our own Final Days because they probably were afraid of the monsters too and they should have a low aether structure that is similar to humans/cat and bunny people/elves/elves with scales/potatoes/demi giants and demi giants with fur.

Coming back to Elidibus I think this could be used to argue against him using Dynamis for a Limit Break because it means there is no known instance of an Ascian using Dynamis. So we only have the officially stated information to go on which says Ascians are not affected by and not (really) able to perceive, let alone control Dynamis.

That doesn't rule him using Dynamis during the WoL fight out completely of course but I think it makes it a lot more unlikely again.)

...perhaps it's just aether but what Meteion noticed was that we channeled Dynamis in addition to Aether when surviving an attack that would otherwise totally obliterate us, against all odds.

That seems like a really good explanation to me.

(I rewatched that part of the Endsinger fight and I think it really can be interpreted like you said:

We are fighting the apocalypse at the edge of the universe and we are using our Big skill to protect ourselves (and per our survival indirectly the rest of the universe, as well) against total oblivion in a space full of Dynamis. So the skill itself is probaly aetherial in nature but in this moment we just had so much determination and will to live/to protect everyone that Dynamis amplified it enormously. The fight with Zenos shows how we can boost ourselves with Dynamis, too, after all while still using what normally are aetherial skills (if you are a mage at least).)