"Who, WHAT are you?" *main story spoilers*

[Anonymoose]

Was it explained how Ysayle learned how to summon?

Not explicity, but it has to be the Ascians, doesn't it?

Before Shiva, in Patch 2.3, Lahabrea says that Eorzea has always been "fertile soil for divine seeds" (recall that Lahabrea always refers to primals as "the divine", almost mockingly) and that people will create a new god if they're given the tools and the Ascians "nurture the gifted" (Ysayle). Then, when Ysayle does summon Shiva, Nabriales is looking on and says that Lahabrea will be pleased. And then in 2.5, Nabriales says that he suffered Lahabrea to merge man and god and you undid all his hard work (by causing the deiform to withdraw from the vessel).

It seems too much to be anything else, imho. The only question is how they approached her, and in what form.

[MilesSaintboroguh]

When in doubt, blame the Ascians.

[Morningstar1337]

When in doubt, blame the Ascians.

'dem Ascians! Always starting wars and twirling their mustaches an chasing pidgeons and sabotaging the races?

Wait...did I get them confused with Dick Dastardly? :P

[Berethos]

It seems too much to be anything else, imho. The only question is how they approached her, and in what form.

My guess would be as the "Paragons" the way they did with the beast tribes, with a focus on convincing her that they could help her "reincarnate" Shiva more fully to carry out her own goals.

[PArcher]

My guess would be as the "Paragons" the way they did with the beast tribes, with a focus on convincing her that they could help her "reincarnate" Shiva more fully to carry out her own goals.

And yet the Archbishop knew them as Ascians. So that's not out either

[Cipher_Zaabiz]

But ysaile used the power of the echo, to turn into shiva and the echo is only given by hyadelin.

On the other hand the ascians used some echo to fuse into prime ascian, too.

[Vexander]

But ysaile used the power of the echo, to turn into shiva and the echo is only given by hyadelin.

On the other hand the ascians used some echo to fuse into prime ascian, too.

The Ascians also gave the Echo to a Sahagin. I think it's a power Hydaelyn and Zodiark both can hand out, and that Zodiark hands it out through the Ascians.

[Anonymoose]

My guess would be as the "Paragons" the way they did with the beast tribes, with a focus on convincing her that they could help her "reincarnate" Shiva more fully to carry out her own goals.

And yet the Archbishop knew them as Ascians. So that's not out either

But ysaile used the power of the echo, to turn into shiva and the echo is only given by hyadelin.

The Ascians also gave the Echo to a Sahagin.

Seems like a loose end that shouldn't be a loose end, right? We know so much, but can't point to where the plot threads meet.
I've been doing research, just because it's on my mind again. I'll try to lay it out while weaving in responses to the above...

Background

The Archbishop seems off the Mothercrystal's radar (no mention of a message from Her, no Crystal of Light), yet he summoned a primal into himself. I thus consider it likely that he was gifted transcendence by Elidibus, as was the Sahagin elder. (How? Hells if I know, but everyone, including the elder himself, pointed the finger at the Emissary.) Thordan knew of the Ascians, but his knowledge seemed to stem more from folklore than a mission from the Mothercrystal.

Not true for Ysayle. She was chosen. She heard Her message; she received a Crystal of Light.

After all is said and done, Ysayle uses telling language in reference to what transpired: she reached out to Saint Shiva to forge a peace between man and dragon, knowing that [A] Shiva would return as a primal, [B] it would cost to Hydaelyn dearly, and [C] it was a nigh unforgivable transgression to burden Her so. She tells Hraesvelgr that she summoned Shiva's soul, that she offered her own body as the vessel for its rebirth, and that Shiva had made her heart known to her (and then the wyrm brings that delusion crashing down on her).

However: before, during, and after Shiva's appearance, Lahabrea and Nabriales (imho) blatantly admit that it was their doing. This keeps right on going into the quest to unlock Extreme, where Urianger says, "In her redoubled strength I glimpse the dark hand of the Paragons."

Interpretation

Ysayle, a lonely, starving orphan is chosen by the Mothercrystal and gets visions of truth by way of a chance encounter with Hraesvelgr. She returns to Coerthas and champions the heretics to bring an end to the Dragonsong War (poorly predicting both Nidhogg's ambitions and how the dragons will act once she presses into Ishgard). Shiva is already a saint amonst the heretics; Ishgard knows all about their worship of she who lay with dragons (allegedly), so Ysayle's story gains her movement some traction.

This is what the Ascians harness. Someone intervenes as part of the Project Thordan the Man-God arc. Presumably, this happens after 2.0, meaning that Hydaelyn had already fallen silent and couldn't have done her Toto-Rak thing, where She spent Lahabrea's entire speech whispering, "This is the thing I was warning you about. This thing is a servant of the Darkness. This thing is a servant of Evil."

Ysayle comes out of this meeting knowing how to summon, and knowing that what she summons is technically a primal. But she believes that it really will be the soul of Shiva, that (if Shiva accepts) she will never be alone again, and that she will have been blessed with true meaning and purpose. After a cost-benefit analysis riddled with bias, she decides to ahead and transgress.

But who the hells does she think she talked to? Is it weird that we don't know that? Did I miss some text? Is supposed to be more obvious?

On one hand, Ysayle knew Hydaelyn's message, had a Crystal of Light, spoke to Midgardsormr, and told the Warrior of Light to "hear, feel, think" and "lead those who walk after" to their face. She managed to pick up all that condescension without picking up a general description of The Adversary?

So the origin of the information could have been disguised... as what?

On the other hand, it feels plausible that (since we're already assuming that she was so desperate for meaning and companionship that she summoned a primal) we're meant to assume that (like Tiamat) it wasn't enough to dissuade her that supposedly-useful advice came from masked men in black robes. But she never mentions that last part. When going over her list of poor decisions, you'd think "I knew summoning a primal would cost Her dearly." might have been followed by, "Come to think of it, the guy with the Kanye shades was a red flag, too."

EDIT: A Favorite Theory

Ysayle knew well her violations, but had misplaced faith in her righteousness. She knew she would summon a primal, but which primal made it okay. She knew that it would dangerously stress Hydaelyn, but that Hydaelyn chose her made it okay. She knew that this path would raise a mountain of dead, but that she would target the liars in the Pillars and put an end to a thousand years of war made it okay. She was a sinner, but she was going to get the job done.

So it seems somehow less appropriate to me if she didn't know where she was getting her information from.

It's more consistent to me if she looked an Ascian dead in the face (okay, mask) and convinced herself that it was permissible to use its knowledge because she wasn't going to fall prey to its schemes; that she was, as always, the exception. The primal would be the benevolent Saint Shiva, and she would summon it into herself, protected by Hydaelyn's blessing. She would be in complete control, so all she had to do was stick to her righteous cause and give up the power when the job was done, and no permanent harm would come of it.

All the while, she would be failing to see that in succeeding to merge man and god, in breaking open the Steps of Faith, in terrifying the people of Ishgard and inspiring ever more desperate prayers to the deified saints of the founding King and his Knights Twelve, and in dragging the Warrior of Light in the middle of the conflict, she was doing exactly what the Dark wanted her to do, and Hydaelyn's silence was never an affirmation that she was heading in the right direction...

I think that's how I'd do it...

But I'll keep thinking.

[SaitoHikari]

Before I launch into a stupid crackpot theory, has there been any documented instances in which an Ascian orchestrates events which directly result in a confirmed death of an echo-user (as in, one who has the echo bestowed by Hydaelyn)?

Ysayle doesn't count because she was killed by the Garleans.

I'm guessing there's a pretty big reason why Elidibus is initially insistent on trying to recruit echo-users, and it might tie into the unspoken 'Ascians don't attack unless confronted by a hostile enemy/attacked first' thing, and why we didn't just get tossed off the island after defeating Bismarck. But of course, it's a variation of the whole 'we're probably Zodiark/carrying a fragment of him in some way' theory.

[PArcher]

Before I launch into a stupid crackpot theory, has there been any documented instances in which an Ascian orchestrates events which directly result in a confirmed death of an echo-user (as in, one who has the echo bestowed by Hydaelyn)?

What about the Isle of Val?