The thing about the Hydealyn and Zodiark situation is that arguably Hydealyn only made it worse, while the summoning of Zodiark actually allowed Etherys to survive. There are two reasons for this - Hyaelyn laid two plans to save the people. The first was to sunder everything to allow them to be more readily affected by dynamis. The question though is why? It would certainly stop the creation magicks from being corrupted, but the result was to make the people and the souls they carry vulnerable to the same corruption. The second plan was for the epeople to flee Etherys and "never look back" but that plan would have ultimately led to disaster. Once that ship departed it would have been beyond the lingering protection that the planets Aether was providing. Like as not every soul on that ship would have died as people turned and more and more became the monsters they were supposed to flee.

Zodiark's protection of the planet lasted thousands of years. He was rendered completely inert by the departure of Elidibus and the sundering. In his role as the mediator he was to see the diveded opions reconcilled, i think this may have played into his promise to Azem. When we consider why elidibus tried to have the WOL killed, it was always to keep the balance between the Light and Dark. He didn't want to risk another 13th or a 1st. The years robbed him of his purpose and memory, but ultimately he wanted to reconcile both parties.

Had Hydealyn not murdered everyone and sundered the planet, it is likely that he would have suceeded and i wonder if this is something that he had left Zodiark to do. Azems involvement in this is important, and one I hope is explored later on.

We also have to consider why hydealyn refers to people as "her children" I suspect it is because for all purpposes that is exactly what they are. New arcane entities created and imbued with fragmented souls that then became the life forms of the planet. Essenentially all life is a product of her creation.

I think Azem would have been against summoning Zodiark for the same reason he/she was agianst Hydealn. The cost was too great. That said, those who summoned Zodiark did so of their own volition, they were martrs who choose to die to give hope to a new future. Venat and Hydealyn's actions though, were imposed on the majority. I think that is also why Azem would have opposed it. Though her intentions were to save the planet. The cost of her actions far outstripped that of summoning Zodiark. With enough time, they likely would have found a solution to Meteion. Or at least I believe they would have. We never got Elidibus' answer to sacrificing the new life to resurrect those scrificed, But i think it was likely something he would not have agreed to. We also don't knwo what the "life" they were going to sacrifice was. It is possible they were simply refering to the many monsters that were around.