Any loremasters recognize the tenticle in the trailer?
Whatever it is, it seems to be underneath Moonrise Towers and demolishes it from within. Perhaps a Nautiloid?
I think you are right about that. Something like https://forgottenrealms.fandom.com/wiki/Slarkrethel would be too far-fetched. Although it would be exciting to meet another unknown power, besides the already known ones. It would at least be a raison d'être for spells like Water Breathing.
