Well, this is interesting. It seems something DID happen to Isibis. The writings I found were by a small band of survivors that sought shelter underground as something swept over the region from the north “Like the darkest nightmare”.
One piece of graffiti is a note saying that “Nothing remains here but ash. The Totem walks. We shall go south.”
Obviously a last message. There are no other references to this “Totem”
I’m going to return to the Lighthouse tomorrow, but I shall travel by land rather than sea, walking north of the Warden Stone.