Major Spoilers for all Expansions - Some general things I didn't understand

[Cilia]

If we're on the topic of things we still don't understand:

1. Are Darkness and Light elements, just as Lightning, Water etc. are? If so, what's an example of Astral Light and Umbral Darkness?

2. There are three types of aether in a person, it seems: corporeal, soul, and memory. Can you create more memory aether by making more memories, thus a longer life adds more to the lifestream than it took when it dies?

2a. Could this have been how the overall amount of aether was supposed to grow and increase in the original ancients' plan to "raise up life to harvest for Zodiark"? Cus the lifestream seems to be a closed system. Since the aether present on Etherys post-final days came from Zodiark in the first place (he'd restored life to the world), where else would you get the extra you'd need to sacrifice back to him to get something new? If you aren't adding new aether somehow, then you're just shuffling the same finite amount about, and if that's it then you'd have to give up part of the planet's ability to sustain life for that second sacrifice no matter what. Cus you are just sacrificing back part of the aether he gave you to fix it in the first place. If no new aether is found or created, equivalent exchange (and thermodynamics) isn't respected and that does my head in. lol

I'll cover 1 down below.

2. This is just conjecture because I don't think it was ever touched on heavily by the story, but the gist of what we've been given is that every living thing has a natural expiration date (even the Ancients), and living beyond that will start to cause memory and personality degradation. This is why the unsundered Ascians needed their memory crystals; unlike their sundered pawns who use them to remember their Ancient selves, the unsundered Ascians use them to keep their memories and personality straight because their unnaturally long lives will otherwise take a toll on them that reduces their cognitive abilities. By the end only Emet-Selch is still using his, with Lahabrea having seemingly given himself over to his Hephaistos "self" and Elidibus having abandoned it to focus on his duties; and Emet is by far the most effective for it.

So to directly answer the question: theoretically but there's still a limit to how much memory individuals can hold, so a longer life won't add to the Lifestream.

2a. To my knowledge the plan had nothing to do with memories, everything to do with nurturing the planet to use some amount of its living things as blood sacrifice to restore the Ancients who sacrificed themselves. The Final Days didn't destroy the Ancients' souls as it did with the victims in our own time, and the planet was in an inhospitable (if not uninhabitable) state but it still had all of its aether. Presumably. They just had to nurture the planet to produce enough souls to sacrifice to Zodiark for what they really wanted.

Did Zodiark respect thermodynamics, and thus require more aether to produce whatever you wanted since entropy is a thing? Well that I couldn't tell you because it's magic, and magic works however the writer(s) want it to work.

The devs have stated that Light and Darkness are not a 1:1 parallel with Umbral and Astral, and act as both aspects and elements. Polarities might be a better word to use. But some people might confuse that with aspects as well. That's why I used the Adverb analogy, since I makes the most sense.

To get more specific on this...

Light and Dark(ness) roughly correspond to Umbral and Astral polarity, respectively, but they also act as mutually destructive elements in and of themselves. This is because Light is essentially non-elemental aether, while Dark is all-elemental aether. The six elements also trend toward Astral or Umbral polarity on their own (with Fire, Lightning, and Wind leaning Astral / Dark; and Earth, Ice, and Water leaning Umbral / Light) but can be shifted to the opposite polarity (Astral Lightning being a thunderbolt vs. Umbral Lightning being static electricity, f'ex).

Notably Eden Shiva (Ryne) uses primarily Ice but due to her host conflating that element with its typically strong Umbral / Light polarity is also able to transform into a bootleg Hydaelyn; and the two eldest primals use the three elements leaning toward their polarity during the Trial fights against them.

[LilimoLimomo]

1. As far as I understood it, Dynamis is essentially the counterpart to Aether. Dynamis creates life and gives it form, and Aether fills that life with all its aspects, darkness, light, earth, fire and so on. Why do Primals need Aether crystals to be summoned, whereas the inhabitants of Ultima Thule are entirely composed of Dynamis?

Primals don't need aether to be from crystals, crystals are just a common way to store quantities of aether. Aether from anything will do, though, including the souls and bodies of followers as shown in the scene that introduces Ultima Weapon in ARR. Dynamis is just a different kind of matter. Think of Aether as normal matter, and Dynamis as emotional matter.

2. Aren't the Twelve essentially Primals with extra steps?

I wouldn't say that. Primals are born of prayer and belief and stuff, and importantly, they have souls. But the Twelve are just arcane constructs that contain "fragments" of souls; and while they pass the Turing Test, the explanation the game provides makes it debatable whether they even have sentience.

3. When we use the Azem crystal to summon people from other dimensions, where do they come from? From the Shard Worlds or from alternative versions of the Source? Do we form them with Dynamis? How do we know it works, does it work like a job crystal?

We haven't been provided with a precise set of rules for the crystal, but when NPC's have been summoned with it they have always come from the same Shard we are in. It doesn't seem like Dynamis plays a role, but rather that the actual entities get summoned. Beyond that we'll have to wait and see whether the writers expand on this. We know it works because when we use it it works.

4. Why can the Omicrons easily resurrect beings that have died? Doesn't that make death inconsequential to the storyline in FFXIV? For example: In the Aetherstream where we fought against Amon, we saw Haurchefant's soul. Why can't we encase it in a crystal, bring it to Ultima Thule, and resurrect Haurchefant there?

I think it's important to recognize that Ultima Thule is playing by its own rules. In Ultima Thule, reality is dictated by emotion. So you can create anything by just emotioning it into being. But it's important to understand that these Dynamis-based beings are not truly being resurrected; they are simply simulations. So if you made a Haurchefant in Ultima Thule, it might look and act like Haurchefant, but he would only be as real as the recreation of Amaurot in the First.

5. When we speak to Metrion in Ultima Thule, Hythlodaeus and Emet-Selch appear and summon a bed of Elpis flowers. Why can they do this? Why do they have consciousness, and even more importantly, why do they still have the power to create things? Shouldn't they just be projections? And why do they remember Metrions doings? Didn't it get wiped?

Hydaelyn gave the Azem stone an additional power just before her death; I forget the exact wording but it was basically the ability to reconstitute things. This is how the Warrior of Light is able to bring their friends back even though their bodies and souls had been dispersed into things like air, wind, and stairs. Similarly, we were able to summon and reconstitute Emet-Selch and Hythlodaeus from their "half-faded" souls. And they had enough juice in them to do a single creation magic. Unlike many of the other "recreations" in Ultima Thule, these two Ancients aren't formed from Dynamis, but are in fact the real deal. As for why their memories are back, there are several points in Endwalker where people mention that when you die you get your wiped memories back. Since both Emet-Selch and Hythlodaeus had died, they got their memories back, so those memories were intact when their souls were summoned back for one final performance.

[Eloah]

To get more specific on this...

Light and Dark(ness) roughly correspond to Umbral and Astral polarity, respectively, but they also act as mutually destructive elements in and of themselves. This is because Light is essentially non-elemental aether, while Dark is all-elemental aether. The six elements also trend toward Astral or Umbral polarity on their own (with Fire, Lightning, and Wind leaning Astral / Dark; and Earth, Ice, and Water leaning Umbral / Light) but can be shifted to the opposite polarity (Astral Lightning being a thunderbolt vs. Umbral Lightning being static electricity, f'ex).

Notably Eden Shiva (Ryne) uses primarily Ice but due to her host conflating that element with its typically strong Umbral / Light polarity is also able to transform into a bootleg Hydaelyn; and the two eldest primals use the three elements leaning toward their polarity during the Trial fights against them.

This better illustrates what I was trying to say, thank you.

[JepMZ]

The first part, I can get behind. The second, I don't understand. The flood of light was astral and yet it left everything it touched in stasis, which we're told is the umbral quality. So... it was an astral flood of umbral light??? Same for the flood of darkness. It left everything it touched in a state of overactivity that ate away all free aether (and apparently merged the lifestream with the physical world leading to undeath). Heightened activity is astral.

Maybe there just isn't really an astral or umbral aspect of light and dark, respectively.

There's some confusion here. Light is always astral. And darkness is always umbral. It's never the opposite. The devs originally stated astral is activity and darkness is passiveness, but this concept has never been brought up or mentioned in game ever before ShB. It did have me theorize the 7th umbral is light aspected. ShB gave a "plot twist", that Eorzean got the properties of light and darkness wrong all along. But it literally changes nothing of any mentions of darkness and light in the entirety of the game because they never before used polarity concept for anything. It literally doesn't matter if light is active energy or static energy before. Now we have an in-game mention for the first time that Light is passive and Darkness is activity. The "plot twist" isn't gonna be a real plot twist for most people because they wouldn't heard the devs' old explanations in the first place. It's only in ShB and forward they use polarity for in-game phenomenon.

[Zero-ELEC]

It is possible that the game has said "we are Azem" and I'm not remembering. I just know the game "hints" at it heavy-handedly. Sort like how it's doing the same for Golbez currently. This game has a lot of context clues. Though anything from someone in the modern day, like Urianger, is meant to represent the inference of the player, since they are gaining that knowledge as we are.

They definitely outright say that the WoL is a shard of Azem, many times.

The message about Azem's armor is a one off conversation in-between quests, so it's easily missed.

I have found no evidence of anything about Azem's armour at all, anywhere, including lore search/gamerescape. I looked. When I went through Elpis I also checked regularly for any new one-off conversations when originally playing through the expansion and do not recall anything of the sort. What quest was it? What section of Elpis?

And the memory Elidibus has has Ancients in it, so it has to be before the sundering.

The memory with the Warrior of Light is explicitly called out as Elidibus as post sundering. "Sundered though you may be, you fought for the world's salvation. For hope." He then reaches out and presumably possess the Warrior of Light, given his next line: "Ahhh, it swells within me. Empowers me. Now — now I may carry out my mission.". This is from the quest Faded Memories.

While I'm not providing, the "answers" some people want, I am giving example of the information we have been given. But if I'm not believed, where is the information to the contrary.

Friend, you can't prove a negative. The burden of proof is on you.

We know the Echo manifests in everyone differently, we know the Echo is the remnants of the Ancients creation magicks, we know recalling the past is a common Echo ability, we know ours has some specialty, and we know Azem's specialty was the summoning of allies. So it makes sense to link all those together.

The Echo is not remnants of the ancient's creation magicks. It was explicitly an ability the ancients possessed, but not creation magicks. We see this with Venat guiding us through the Echo but not involving creation at all. We don't know that our echo has some specialty at all. There's no indication of that? And Azem's power of summoning allies is explicitly a spell. One engraved into Azem's crystal.

[Luizgazen]

In SB it is implied our "special echo" is actually gameplay related, the ability to see castbars and aoe markers, as when Fordola is attacked by Lyse and Alisaie and with her copy-echo evades all of their attacks and says she has "seen" them already, making the ability to foresee which attack your opponent will use and where it will land even before they start moving an echo ability, and since we don't really see Arenvald or other characters with the echo using it, it must be an individual ability we have been using since the start

[Eloah]

quote

I'm out. People can believe what they want, until they get their "hard proof" because apparently the breadcrumbs the devs give us, and that I have pointed out, mean nothing.

[Zero-ELEC]

I'm out. People can believe what they want, until they get their "hard proof" because apparently the breadcrumbs the devs give us, and that I have pointed out, mean nothing.

Look, I want to believe that what you're saying is true. You have no reason to lie and I have no reasons to believe that you're lying. I want to see the breadcrumbs that you say are there. But I need to actually see the breadcrumbs so that we can be in the same page. That's why I'm asking for particulars. Which cutscenes? Which dialogues? I'm not asking for "hard proof", either. I'm asking for the hints.

I can point you to places that explain what I mean. The cutscene right before the Warrior of Light trial where it's explained that "yours is the seat of Azem", the cutscene where Elidibus "possessed" the Warrior of Light explicitly calling them out as sundered, the cutscene in Elpis where Venat induces the Echo and explains how it works and says nothing about it being creation magicks. I point those out because I want you to be in the same page as me, I would hope you want to me to be in the same page as you.

[Alleluia]

I'll cover 1 down below.

2. This is just conjecture because I don't think it was ever touched on heavily by the story, but the gist of what we've been given is that every living thing has a natural expiration date (even the Ancients), and living beyond that will start to cause memory and personality degradation. This is why the unsundered Ascians needed their memory crystals; unlike their sundered pawns who use them to remember their Ancient selves, the unsundered Ascians use them to keep their memories and personality straight because their unnaturally long lives will otherwise take a toll on them that reduces their cognitive abilities. By the end only Emet-Selch is still using his, with Lahabrea having seemingly given himself over to his Hephaistos "self" and Elidibus having abandoned it to focus on his duties; and Emet is by far the most effective for it.

So to directly answer the question: theoretically but there's still a limit to how much memory individuals can hold, so a longer life won't add to the Lifestream.

2a. To my knowledge the plan had nothing to do with memories, everything to do with nurturing the planet to use some amount of its living things as blood sacrifice to restore the Ancients who sacrificed themselves. The Final Days didn't destroy the Ancients' souls as it did with the victims in our own time, and the planet was in an inhospitable (if not uninhabitable) state but it still had all of its aether. Presumably. They just had to nurture the planet to produce enough souls to sacrifice to Zodiark for what they really wanted.

Did Zodiark respect thermodynamics, and thus require more aether to produce whatever you wanted since entropy is a thing? Well that I couldn't tell you because it's magic, and magic works however the writer(s) want it to work.

Can you direct me to the source that says Emet was using his crystal and that the crystals were actually given to the amaurotine officers pre-sundering? I was under the impression that crystals were something the unsundered made (with Emet doing the actual crafting) to facilitate the raising of the sundered soul shards to their seats and jumpstart the recovery of their memories. Not a pre-sundering thing the convocation regularly did. Otherwise, there wouldn't be just the Unsundered's memories of Hermes in the Fandaniel crystal, for instance, but also his predecessor's memories. Am I forgetting something in Elpis or Amaurot that touched on this?

And re: the final days -- the ancients were just stabbed/chewed to death etc, yeah. But the creations that their creation magicks made were blasphemies. It seems likely to me that that caused at least some loss of aether. The aether is used to manifest a creation which is then immediately annihilated by dynamis and turned into a blasphemy? Or perhaps the blasphemies are just a result of the dynamis reacting with a part of amaurotine's aether, but it couldn't turn the whole soul b/c of their aether density being too thick? Either way, the "aether to no aether" thing still happened. Or else the blasphemies wouldn't still look the same. Its like the dynamis attack was only able to peel off a layer of aether from them about the density of a familiar and then corrupt that. And then in modern day we all have the density of an amaurotine familiar, so it just corrupted modern people whole.

I'm still not certain whether I buy that the aether is just annihilated when confronted with dynamis, cus in an antimatter/matter annihilation reaction(which this has been oft compared to) BOTH things are annihilated. But as we saw: there was a big old monster, animated by the emotions of the person it used to be, left behind when the dynamis attack hits. So something must physically be there, and (barring some unknown third force) that something must be made of dynamis if there is no aether present, thus dynamis was not annihilated in the reaction. So, I think it makes more sense that aether and dynamis can become one another and the aether just experienced a state transference (like matter to energy transference). But this is just me rambling now. >_>

Or as you said, the writers are looking at this going "Laws of thermodynamics? In MY magic system? Ha!"

[Enkidoh]

In SB it is implied our "special echo" is actually gameplay related, the ability to see castbars and aoe markers, as when Fordola is attacked by Lyse and Alisaie and with her copy-echo evades all of their attacks and says she has "seen" them already, making the ability to foresee which attack your opponent will use and where it will land even before they start moving an echo ability, and since we don't really see Arenvald or other characters with the echo using it, it must be an individual ability we have been using since the start

That's just a myth/misconception that just refuses to die like a stubborn Ascian and is quite frankly not true. Fordola doesn't 'read your mind to sense your attacks' before they happen through the Echo, she senses very subtle fibrations through the aether which is why she's so easily incapacitated with Moen's wand thingy blasting a large amount of aether at her, it overloaded her senses and stunned her. Fordola's Resonant power isn't even fully like the Echo (she can't see proper memories as a fully interactive vision for instance, but merely sees fragments of still images like a broken Powerpoint slideshow) - not surprising given it was meant to give magic powers/aether manipulation ability to Garleans (it also was not copied from the WoL either - Krile served as the model for it and she was hardly the most potent in the Echo by her own admission, being more attuned to animals and beasts than being able to read others' memories or understand other languages).

As part of that, the Echo doesn't 'tell' you about telegraphs and AoE fields.... as the devil is always, in the detail. We have ability telegraphs and AoE fields on screen for pretty much everything, even for things that have no souls/aether like boulders and machina which if it really was the Echo telling you that, it would only be able to work with something that has a soul. As inanimate objects/non living entities with no aether/souls also give ability telepgraphs/AoEs, therefore it's not the Echo showing that. It's just a gameplay mechanic with no bearing on the story. The whole game visual interface is just for gameplay purposes, nothing more.

And also ignore the 'Echo' effect buff given in battles too, that's just again a fancy title given for a leg up for gameplay and has nothing to do with the storyline.

It's like the old meme about Aeris in FFVII - "why didn't they just use a Phoenix Down on her?" Because Phoenix Downs are just gameplay mechanics and can't actually bring someone literally back from the dead!" So likewise the Echo here in FFXIV doesn't tell you enemy cast bars and fields of attacks, that's just a fancy GUI function that doesn't even need an explanation, it just is, it's part of the game.