I didn't really have the space to cram it into the prompt, and I didn't want to color other people's ideas too much, but mostly I was trying to imply a threat of a magnitude beyond human comprehension, such that even an entity we perceive as infinite and all-powerful must focus their entire being to fight it.

The conceit here is that God may as well be infinite to us as 3.5 dimensional beings, but on the realm of other Nth demensional beings, perhaps He is not so infinite after all. It's a cosmic horror answer to the question "If God is all-powerful and all-good, why is there evil in the world?" God is busy making sure every last soul on Earth and in the afterlife doesn't become a Cthulu snack.

Glad you liked the prompt, though. Perhaps I should have worded it differently. :)