Originally Posted by
phantombassist
The Eternals were seeded along with the Deviants on Earth a very long time ago by the Celestials, so it has always been my assumption that both groups exist as parts of the the greater Celestial Cosmic System of seeding, nurturing, and in some cases razing worlds. I think they are in a weird area right now because while their powers and origins are completely cosmic in nature, the current approach Marvel seems to have regarding their cosmic line is less Kirby Space Gods/Myth and more warring empires meets wild west.
I agree, the incursions and what they represent (universal systems failing) should very much be a pressing priority for them. After all, they have gone so far in the past as to state that they have a biological imperative to perform their greater purpose (not unlike Apocalypse). I don't think Starbrand and Nightmask fall under the same system as the Celestials, but rather exist as a redundancy system to ensure the genesis process continues and that things stay fresh. The Aleph/Origin Bomb system is another such system. Still, these incursions threaten all the previously mentioned systems, so I have no clue why this isn't on the top of their to do list.