Guild Wars 2

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In Hidden Arcana you can talk to Ogden about the Dragons and the All at the end:

Please, tell me about the Elder Dragons.

Ogden Stonehealer: You already know much about them. But for Miss Delaqua’s benefit…
Ogden Stonehealer: The Elder dragons may be as old as the world itself. They’re more than creatures.
Ogden Stonehealer: They’re part of nature’s workings. They rise and fall on a cycle that spans millennia.
Ogden Stonehealer: Much of what we know about them comes from a document written by the first humans to walk the face of Tyria: the Scroll of the Five True Gods.
Ogden Stonehealer: It is written in an ancient dialect, therefore it is subject to interpretation.
Ogden Stonehealer: In it, the gods revealed the names of the Elder Dragons: Mordremoth, Kralkatorrik, Jormag, Zhaitan, and Primordus.
Ogden Stonehealer: There is one other name listed, but it is illegible, lost to time. I suspect this is the deep-sea dragon.
Ogden Stonehealer: The gods expound on how Tyria’s health is tied directly to them. This portion is somewhat abstract, however.
Ogden Stonehealer: There are varied theories on what it means, but I believe it refers to the natural balance of magic.
Ogden Stonehealer: Too much magic, and the world spins out of control. Too little, and it crumbles into darkness.
Ogden Stonehealer: The last time the Elder Dragons awoke, they wiped out almost every intelligent race on the planet.
Ogden Stonehealer: It is from this low-magic environment that the gods built the world as they wanted it.
Ogden Stonehealer: They are the ones who brought humans to Tyria.
Ogden Stonehealer: The gods shared the magic stored in the Bloodstone. That is a complex tale for another time.
Ogden Stonehealer: Slowly, more magic seeped back into the world from the dragons, over thousands of years. Cultures evolved again.

How does this all tie into the Eternal Alchemy?

Ogden Stonehealer: Ah yes. Only you asura would attempt to quantify nature itself. But then, your people are somewhat limited. No offense.
Ogden Stonehealer: By attempting to define the undefinable, you actually move further from the truth rather than closer to it.
Ogden Stonehealer: The Eternal Alchemy, nature, our world, the All—however you want to name it—is beyond understanding.
Ogden Stonehealer: We can only grasp portions of it. Even the Elder Dragons are small relative to the All.
Ogden Stonehealer: We see only certain layers of the Mists, the Elders, and Tyria. Anything beyond that is hidden from us.
Ogden Stonehealer: We must content ourselves with first understanding what’s before us.
Ogden Stonehealer: Right now, the Elder Dragons are the most critical to understand.

Hidden Arcana*

Arcana Obscura is part of Episode 8, which doesn’t feature this. Either way, all of this is well known and had been commented upon a lot during Episode 5’s release. Pretty much we’re seeing a lot of hints pointing to “killing the Elder Dragons without replacement will destroy the world” – the “without replacement” comes from Ogden in the same episode who states the Brotherhood of the Dragon believed Glint could become an Elder Dragon given time and magic. This leads folks to think that’s the purpose of Glint’s egg, and why Tequatl got a power boost. Given that the Pale Tree is indeed a minion of Mordremoth, she and the sylvari could also – theoretically – function as such (even Malyck could).