This adventure previews the shoggoth, a monster from the Tome of Beasts (Kobold Press).
Adventure cannot be readily solved by direct assault, so groups optimized for combat alone may find it difficult or impossible to succeed or, indeed, survive. If a direct assault and toe-to-toe combat is the goal, characters of level 17 or better are called for. It's also excellent for ending a campaign.
This adventure doesn't have any pending change requests.