The Lamp’s Shadow and Milden Span

Various clues:

This book contains all the invocations and prayers you’ll need to learn the truth, Mr. Dory. The dark god’s faithful are wary of new converts. But learn the words, and they should accept you soon enough. Seek their pulpit in the evening shadow of Frother’s Lamp. Praise Tharizdun!

Adventurers review the clues found from Mr. Dory’s quarters. Firbolg spends several hours reading a book penned in a strange language. The party doesn’t know what or who could be changing/rewriting history, but they have agreed to log their experiences in a notebook as a backup. Something has changed Mr. Dory, and he was a lot more powerful than anyone would have suspected. The book mentions Tharizdun and Sgothgah several times.  Random scraps of paper are filled with illustrations of tentacled creatures in chains, along with a more disturbing note “more bodies to feed the young one”.
The party decides to investigate an old abandoned lighthouse – named Frother’s Lamp in the Lower Quarter. Quixsy intimidates the locals for directions and information – they are quick to help. After many twists and turns through the dirty alleys of the Styes, our adventurers arrive at a bridge named the Milden Span. On the opposite side of a filthy river a ship’s hull is embedded in the mud. Dilapidated buildings are stacked all around.
The bridge is slick with a questionable weight-bearing limit. Sargassum runs across the water to secure a rope for extra support/in case someone slips. Once Sargassum reaches the other side, he detects movement on the ship’s prow. Mounds of garbage litter the entire upper deck. Tentacled monsters (Scum) burst out from their hiding spot and attack!
The Scum put up some resistance but eventually are defeated by our heroes. The scum’s tentacled psychic attacks did some significant damage.  Healing spells and powers are used to heal wounded party members. Not much of interest can be found on the deck of the ship -rats, garbage and dead scum. Adventurers bust open the double doors embedded into the earth. This part of the ship is more rotten, squishy and moldy than the outer deck. Snaps leads the way down a hallway – more doors are at the other end. Before she can get there, the floor creaks and breaks away, the tortle barbarian, Snaps, falls through the floor…