[@Cultural Titan] I feel like trapping Nyarlathotep's soul would be a good option, but it would probably take a lot more than Raven's lantern to contain it. I think the main way of defeating them would be for the Light side to find a way to break the connection between Nyarlathotep and the darkness of humanity, because without that they're not a very powerful being. Then they can be sealed away.

How they'd go about doing that? Well, we can always find a way via space magic or something.