Nael Van Darnus vs Shadow Lord

[Vydos]

That's my guess, personally. He's being controlled by Bahamut, who is most likely in Dalamud. It's a really weak theory, but Megaflare kinda gives it away, I think.

I never looked that far into it. But you do strike a very good point and also makes some sense if you think about it.
Perhaps the Allagan managed to seal Bahamut in the past and decided to send him far away from them. It also might not be a coincidence that Bahamut and Dalamud practically sounds the same. Perhaps it's actually how the allegan's pronounced bahamut back then.

At first I thought Odin would be sealed inside but odin is way too small for such a large entity. Bahamut on the other hand...