What is Zodiark?

[Morningstar1337]

Also, if all of the gods, Hydaelyn included, turn out to be primals, than the logical solution to all of the problems of FFXIV would be to simply put a stop to belief entirely... Which would probably require the mass genocide of all species, everywhere, throughout the cosmos... Admittedly, that would make for a very interesting plot twist, but I don't think we've seen any villains in FFXIV so far who have that kind of special brand of Kefka level insanity.

Garlemald comes close. They already wanted to exterminate the Beast Tribes because they an summon primals and it is implied that once Regula comes back from Azys Lla and tells Varis about Shiva then their plains will be kicked into overdrive, their ends are likely to be in the worse case scenario, this specific omnicide.

And since Nael took cues from Sephiroth, it's possible that Regula or Varis would take on this grand of insanity (Jester motifs would be more unlikely)