Godbound: What is the Doom of Kreivok?

Kreivok is a Realm living on borrowed time as it's Celestial Engines decay. Long ago, someone or something made a prophetic declaration on the coming the Inevitable Doom which would invariably spell the end of the Realm and ultimately lead to it's undoing and then fall into the Uncreated Night. But what is it?

Need to find the artist on this one, too.

Honestly I don't know. Only theories exist on the matter. This is not helped by the little amount of written material on the subject by Kreivok's inhabitants making it just as much of a headache in-universe. Most information on the Inevitable Doom is from oral folklore leaving very little coherence to the story.

• The most logical end for Kreivok is for all warmth to die as the Celestial Engines evaporates, leaving the place a cold and lifeless wasteland where no living creature can endure. Early signs of this happening would be a difficulty in creating flames.
• The alternative is that the proper energy flow has gone wrong and the Engines are producing the right amount of warmth. This would therefore mean that some other part of the Realm is getting warmer or, perhaps, collecting the energy...until it explode in a furious inferno.
• Some ancient power and foe is what will bring about the Doom, awakening and unleashing it's fury and sparing no lives. Frozen Fae-Giants covered in layers of rime, fur and metal crushing mountains or ancient Liche-Lords come to mind as does kaiju-sized Misbegotten.
• The honored and collected dead of Kreivok are not like those of Norse Myths: rather, they bring fear as the dying warriors are taken by metallic birds to lands beyond the ocean. Those rare few who traveled there speak of gigantic iron vaults filled with the hibernating and changed form of the warriors waiting to be unleashed against who or what, no one knows.
• Perhaps there is no Doom and it merely is a myth. Still, who can say for sure that some outside power (such as a Godbound) might not end up destroying the Realm after all?