Solution 9 - Unfounded Speculation!

[Cleretic]

The Dawntrail promotional website doesn't give us a whole lot of new story info (except about the field operations, which I'm EXTREMELY excited about but that's not related to this), but it does give us a description of the actual storyline of the Arcadion.

Here at the Arcadion, you'll find a grand spectacle unlike any other. The realm's greatest fighters pit fist against fist and magick against magick, putting their lives on the line as crowds howl and clamor, each clash more visceral than the last. Step into the arena if you dare, and either rise to become champion, or fall forever in ignominy.

It's a tournament arc! A straight-up no-nonsense tournament arc, too, no extra weirdness like Omega's. At least, that we know of at this point. Which, incidentally, does start explaining those billboards; we're not looking at viruses, or sigils. We're looking at fighter promo art.

Still no clear evidence that the Arcadion is in Solution Nine, but we're still in 'where else could it be' territory.