Is that spiral thing shown in the artwork Razkanar? It's hard to tell because it looks more asymmetrical withh a desending spiral while razkanar seems more like a building with 90degree walls and such. Also if you look at the original SoA naalual artwork mural by Amano, there are several blueish-white Wyrm things. The one in the center bottom could be Saj but isn't he north of Kamhir not south? There's another one on the left that resembles leviathan a bit and another in the east in the sea. On the top left there seems to be a black serpent and the top center looks like some kind of cobra thing.
Could also be a plot twist that the serpentine labrynth is itself the last naakual kinda how alzadaal ruins were the original body is alexander
I have a feeling the inner razkanar will be the site of the final battle as well as the area for the final dungeon crawl content like Walk of Echoes/Limbus/Nyzul Isle were.