The Single Most powerful *thing* in FFXIV?

[Absimiliard]

I didn’t actually consider this but it’s definitely a good point. Zodiark was conceived as a being powerful enough to revert the final days and/or restore the ‘world’ to its original state. While they were only thinking of their own ‘star’, surely Zodiark would need power that can stretch across the cosmos (at least to some extent) to actually be able to achieve these goals? If it was fully awakened then, couldn’t it (assumedly) collapse and re-arranged the universe to see its goals to fruition?

As you say though, biggest weakness is that of any primal, but probably multiplied by 10 because of the size/scope of its abilities. Tempering nearby planets, requiring enormous amounts of aether to materialise, being tied to the consciousness of the Summoners (i.e if they forget their purpose so does Zodiark, or at least I think that’s how it worked).

Zodiark's first summoning created a shield to prevent the Final Days from continuing. The second repaired and reseeded Etheirys, and only Etheirys. The moons of course being considered part of Etheirys for practical purposes, them being part of the same system. The rest of the universe (insofar as we are aware, anyway) was left a desolate wasteland by the Endsong continuing uninterrupted.

Zodiark's purpose was set by a combination of the intent when he was summoned and the will of the many souls within him. This is why he continued to function in his original role as a protector even after losing his heart and all of his summoners being dead.

The problem is we dont know what zodiark would do when completed. It surely takes all the aether away from the planet, but we dont know what it will do in space. Zodiark was powerfull enough to block the effects from dynamis even in an incompleted state. But weak at the other aether.

We're told Zodiark did not siphon aether from the planet. He instead utilized the aether of the ancient souls within him, with the caveat being he would not completely drain them. This was possible due to the sheer volume of aether made available to him by those sacrificed. He could draw from them without tapping into their spiritual aether, which meant their souls weren't at risk of erasure.

Of note, I may direct people for a moment to the in-game Zodiark fight. It's a poor showing to be sure, but we're dealing with an incomplete Zodiark under the control of someone who A.) is completely insane; and B.) has zero experience piloting a primal. It's also important to keep in mind the dark primal was still channeling vast quantities of aether to maintain the shield around Etheirys even as Fandaniel forced him to fight the WoL. To add to this, we're informed the souls inside of Zodiark were fighting back against Fandaniel that whole time. Odds are good what we saw was a fraction of a fraction of what he could do if whole and properly directed. If nothing else, we are shown that he possesses the capacity for some fantastically destructive magic and weaponized creation. I'd wager he very well might be in the running for the most powerful thing overall. Even fragmented, his raw aether levels alone are well past the point of incomprehensibility.