[Spoilers] The Device in DT msq

[Cassar]

My initial theory, which I now am quite certain isn't correct because some things don't really fit, but still is quite fun is the following:
What if that device was originally designed by an Ascian and his or her intention was for it to be kind of a failsafe device: In case everything else fails, and all the Ascians are killed, this relic will remain and humanity alone will accidentally do the rejoining by themselves, due to them being flawed and always looking for more source of power/greed.

This would be extremely interesting because it would require a very smart Ascian to know that there's still a way to win even if they're all dead.

Of course, there are many holes in this theory. First of all, if the device has that kind of power, why wouldn't the Ascians have used it themselves? Also, even though the reflections get rejoined, it doesn't look like the people's souls do. (Unless the people that get born in Heritage Found have a denser soul?)

The second theory that I had - especially when it was emphasized how this power came from the prayers and deep desires of the Lalas from the Source to escape - is that this is some kind of Eureka device, that has the power to do pretty much whatever it is that's required. It seems like there's another condition that needs to be met however, because almost nobody was capable of actually using it.

Finally, I'd like to bring up the fact that the Ascians never got ahold of the artifact. Did they simply not know about it? Did one of them try but was ultimately killed like with Eureka?

[SaitoHikari]

The second theory that I had - especially when it was emphasized how this power came from the prayers and deep desires of the Lalas from the Source to escape - is that this is some kind of Eureka device, that has the power to do pretty much whatever it is that's required. It seems like there's another condition that needs to be met however, because almost nobody was capable of actually using it.

Finally, I'd like to bring up the fact that the Ascians never got ahold of the artifact. Did they simply not know about it? Did one of them try but was ultimately killed like with Eureka?

It's interesting that you bring up Eureka, and other people here are bringing up the idea that it might be an Auracite.

I'm personally of the mind that it is an Auracite that pre-dates the Ancients. In fact, if it is indeed an Auracite that has the ability to grant its bearer's wishes (like the Heart of Sabik amplifying desires, and the ones involved in the Ivalice alliance raid series seemingly changing the bearer's aether to turn them into monsters/avatars along with mentally manipulating them somehow), I see a potential plot twist in that the missing Azem didn't actually 'desert' the Convocation on purpose at all, we are only assuming they did from second-hand information. The key could have pulled off a monkey's paw type of wish, where it trapped Azem somewhere and thus couldn't intervene in what was happening (and/or Azem willingly trapped themselves in an attempt to banish the key forever), and they may have only able to escape due to the Sundering. This would potentially make the key or something related to its origin a potential final boss of this new overarching story.

That said, I'm thinking on something else too... Did the game ever explain exactly what Ozma was or how it worked? Solution 9 got ported into the source with the key's help, but we have already seen something similar happen twice. Nym and the Isle of Val/Eureka also being displaced, and an Ozma was involved in both instances. We are likely to run into a third one finally explaining what their deal is soon, considering this is a heavily IX-themed expansion and Ozma was the secret superboss of that game. Thinking on this further, the primal Eureka sounds suspiciously more like an Auracite rather than an actual traditional summoned primal too, or at least the Ascian involved gave it a primal form and consciousness somehow.

Come to think of it, the Loporrits mention something about how primals were predisposed towards tempering people because of a 'bug' in the summoning method that the Ascians shared with the summoners. I never did many of Endwalker's sidequests, so was it ever explained exactly how this 'bug' worked and where they got the idea for it?

[LilimoLimomo]

The fact that the key's aesthetic doesn't fit with any of the cultures we are familiar with suggests it is from a culture we are unfamiliar with. Which seems like a very appropriate bread crumb to leave players with as we start a new 10-year saga of the game's story.

[Mixawaves]

I think the obvious take is the right one here, and the sigil reveal before the final trial points to the device being an Azem creation. It hit me in the moment that, in addition to the sigil itself, the crystal inside is also the same hue of Orange associated with Azem, and shined that way during other scenes when we were not present. And if so:

Finally, I'd like to bring up the fact that the Ascians never got ahold of the artifact. Did they simply not know about it? Did one of them try but was ultimately killed like with Eureka?

A problem with adding the device (or anything similar) into the history of the Source and Reflections at this point is there should be a good reason the Unsundered were unaware/unconcerned with it. Having it be an Azem thing can ameliorate that, since it's not out of the question that Azem could have had a way to conceal his creation(s) from the Convocation or lock them out of usage.

[Iscah]

Auracite is said to "make manifest one's most fervent desires" and given how the Milalla used it to escape a calamity, and Sphene used it to fuse a part of their shard to the Source as well as transform, its uses can vary.

This suggestion has come up a few times, along with some mentions of Alexander's potential relevance (as it is important in FFIX?) and that swirled up a relevant quote in my mind: Mide was given the summoning horn by Travanchet along with an instruction to wish for her heart's desire.

Having dug up the full actual quote, it seems even more potentially relevant - from The Coeurl and the Colossus:

CID
All right, out with it, Mide. If there is anything you haven't told us, we need to hear it now. We are running out of options.

MIDE
I fear it will not avail us, but...very well. It all began with a curious encounter in my younger days. I was out playing on my own one day when a stranger appeared before me. He told me anything my heart wished for could be mine if I but heeded his words.
In my youth, I did not fully comprehend what the man was proposing at the time. Nevertheless, his words seemed to burn themselves into my very soul. “Reunite the scattered shards of the Enigma Codex,” he said, “and perform the sacred rite before the ruins that yet stand strong against the river's flow. Then, and only then, shall your hopes and dreams become reality.”
With that, he handed me a relic─a horn, with a tip of metal─which seemed so foreign as to hail from another world. It would serve as a catalyst for the “summoning,” he explained. “A gift from your friend Travanchet.” And then he was gone.

Y'SHTOLA
Travanchet? I know the man. Our paths crossed during my time in Limsa, in the days before the Calamity. I might have guessed that the Ascians had a hand in this.
The horn of which you speak was once rumored to reside on Seal Rock. It is a lost relic of the ancients with the power to manipulate the aetheric energy in the very air around us. The Scions have long pursued the horn, fearing the devastation that might ensue were an artifact of such power to fall into the wrong hands.

The horn itself is accounted for, of course - it's currently embedded in Alexander's core - but it sets me wondering if they're trying to connect back up to this plot thread, and what other similar relics might be out there.

The Enigma Codex itself was an odd thing, alien-looking technology at the time of that story, but now with further developments it could possibly be electrope or something like it. We never got a really clear full picture of its history either, IIRC, and I've forgotten what there was because it always felt like a fairly minor detail at the time.

[Cleretic]

A problem with adding the device (or anything similar) into the history of the Source and Reflections at this point is there should be a good reason the Unsundered were unaware/unconcerned with it. Having it be an Azem thing can ameliorate that, since it's not out of the question that Azem could have had a way to conceal his creation(s) from the Convocation or lock them out of usage.

I keep saying this, and I haven't seen a single decent argument to refute it: The Ascians do not need this key, because it does a thing they could already do. They could already cross over into other shards, and by all appearances it was a lot easier for them! The one advantage it had is probably transporting people en masse, and the Ascians don't need that, because they only ever needed one-person transport.

Why would they even care that the mortals pulled this off?

The fact that the key's aesthetic doesn't fit with any of the cultures we are familiar with suggests it is from a culture we are unfamiliar with. Which seems like a very appropriate bread crumb to leave players with as we start a new 10-year saga of the game's story.

And yeah, I think that we're ultimately running ourselves into walls by thinking we have all the answers to this already. This is very clearly a breadcrumb for future stories, there's no way that we can just intuit every single major figure in its history at this point.

[kaynide]

This suggestion has come up a few times, along with some mentions of Alexander's potential relevance (as it is important in FFIX?) and that swirled up a relevant quote in my mind: Mide was given the summoning horn by Travanchet along with an instruction to wish for her heart's desire.

Having dug up the full actual quote, it seems even more potentially relevant - from The Coeurl and the Colossus:



The horn itself is accounted for, of course - it's currently embedded in Alexander's core - but it sets me wondering if they're trying to connect back up to this plot thread, and what other similar relics might be out there.

The Enigma Codex itself was an odd thing, alien-looking technology at the time of that story, but now with further developments it could possibly be electrope or something like it. We never got a really clear full picture of its history either, IIRC, and I've forgotten what there was because it always felt like a fairly minor detail at the time.

This makes me nervous; I already don’t like time travel…and the fact that the city is named Alexandria already gives me red flags.

I just really really really hope Alexandria doesn’t have some janky connection to Alexander and the 12th shard. Like the artifact being the horn from Alexander refined….

I mean I guess if it’s done right…but maaaaaaan.

[Iscah]

This makes me nervous; I already don’t like time travel…and the fact that the city is named Alexandria already gives me red flags.

I just really really really hope Alexandria doesn’t have some janky connection to Alexander and the 12th shard. Like the artifact being the horn from Alexander refined….

I mean I guess if it’s done right…but maaaaaaan.

It would still take some effort to get Alexander (a Source-created construct with no known dimension-travelling powers) over to the Alexandrian shard, if they wanted to make a connection to it, although I have - in a "flippant but it could work" way - previously toyed with a scenario that could make such a thing work.

Specifically, due to the Shadowbringers timeline split there are now two Alexanders, one per timeline. Alexander locked itself away because it tends to absorb aether, but now the 8UE Source has an issue with a particular type of excess aether (conveniently the same type Alexander is aspected to), so maybe that could get cleaned up by having Alexander wake up in that timeline and absorb it. Due to being awake, Alexander is now free to take a trip back to X years ago and drop off Mide and Dayan to become the founders of the Hotgo, spending that excess Light aether to fuel the trip.

So, adding to that earlier idea, we now need to add dimensional travel to Alexander's skill set - and the easiest way to do that would be to get Omega involved and create the real team-up that the Ironworks previously mimicked.

Of course, that still needs Alexander to have some kind of reason to want to go shard-hopping in the first place, but maybe it's just that good at predicting the timeline outcomes and where it needs to be to do... something.

[Cleretic]

I just really really really hope Alexandria doesn’t have some janky connection to Alexander and the 12th shard. Like the artifact being the horn from Alexander refined….

Honestly I find it sorta funny that they deliberately avoided giving us a straight, non-abstracted view of Alexandria Castle; it's gone in Heritage Found, it's not directly shown in the dungeon, we only see a Disneyland-style cutesy version in Living Memory. Because of course they can't show a FFIX-accurate Alexandria Castle, people would just go 'but that's Alexander'.

Also, while we don't know the specifics of the Enigma Codex, I think the implication is that it itself is part of the time paradox; like how the legend of the Hotgo that the Wandering Minstrel pulls from was Mide and Dayan's history made legend, the Enigma Codex is an account of the events of Alexander, being mistaken as blueprints for the machines within Alexander.

[Cassar]

I keep saying this, and I haven't seen a single decent argument to refute it: The Ascians do not need this key, because it does a thing they could already do. They could already cross over into other shards, and by all appearances it was a lot easier for them! The one advantage it had is probably transporting people en masse, and the Ascians don't need that, because they only ever needed one-person transport.

Why would they even care that the mortals pulled this off?

While they indeed have the capability of travelling freely between shards, the artifact - in the wrong hands - is also capable of causing a localized rejoining, as we've seen with Heritage Found. G'raha specifically pointed out how closely similar the phenomenon observed there was to an actual "localized" rejoining.
I think this kind of power would bring the Ascians a huge advantage as they wouldn't need to go through all the arduous process that they know of.
I also have a gut feeling that what Krile's dad said about the artifact was some sort of foreshadowing. I can't remember the exact quote, but it was something like "...We don't know the origins of the artifact, but know this: it is a tool, and like any tool it can be used for good or for evil."

Something also occurred to me. They keep saying how they erred when attempting to rejoin the Thirteenth and caused it to become the void. What if they did try to use the artifact but didn't know how to use it and caused all this mess, and then afterwards they didn't want to do it again? Could be an interesting way to reconnect this plot with the Golbez/Zero storyline, although I think the direction they'll go is by using the artifact to create a path from the First to the Thirteen, bringing light from one to another and essentially fixing both.