Part XIII: Journey to the Bottom of the Bay

When we returned to Illmarsh, we discovered that the mayor had gone missing, along with several other townsfolk. No-one had seen what had happened.
So, we couldn't report our success. Our only lead now was the skum cave at the bottom of Avalon Bay. But how would we get to it?
The answer was simple. Horace Croon, the old man we had encountered on the way in Illmarsh, had been working on a submersible. When we approached him, he was more than happy to lend a hand.
We climbed into the metallic fish - it was hot and very cramped - and it was slowly lowered into the water. Through the windows we could see nothing but blue. As we descended, the light faded, and darkness engulfed us. The submersible began to make frightening creaking sounds, but it held together. Suddenly, we noticed that there was a light shining in the darkness. At the bottom of the lake, built against a submerged cliff, was a fantastic dome of metal and glass, emanating bright light - bright enough to see the surrounding area.

The submersible stopped, and we could see a cave entrance a few hundred yards away. Ferdibrand cast Breathe Water spells, Ellavorn equipped her magical helmet, and we stepped out onto the sea bed. It was an amazing sensation. The weight of the water pressing down on us was incredible, but our magic prevented us from getting crushed.
As we made our way to the cave, Ellavorn's trident lit up. "Something is coming," she said. As we turned, a monstrous octopus, covered with thorny barbs, swam into view and attacked us. Bravely we attacked it as it assailed us with underwater magic. But soon it was defeated, and we made our way into the cave.
At the back of the cave was a glass wall, beyond which we could see a dry tunnel. Cautiously, we touched the glass and found that it was soft, so we pushed ourselves through it and into the tunnel beyond.
The skum tunnels were bereft of skum, their numbers brutally murdered by the alien invaders. But the invaders were still there. Peculiar creatures, born from a nightmare, roamed the tunnels.
We fought tall, thin, faceless creatures that tried to tear us to pieces, fat, tentacled, plant-like creatures that assaulted our minds with psionic attacks, and large, hairy, multi-armed beasts.(That fight was rather interesting. As the fight started, Skalif ran over to the beast, grabbed it, and vanished! A short while later, he reappeared, without the thing. He informed us that he had teleported back to home of the werewolves in the Shudderwood and given them the creature, which they had hungrily turned on.)
During our exploration, we came across a room filled with large glass cylinders, some of which had brains floating in liquid in them. After some experimentation, we worked out the use for some buttons and switches on the cylinders, and found that we could talk to the brains! It was horrifying. Each brain belonged to an Illmarsher. Each one had gone insane. And among them, we found the brain of Mayor Greedle. Through his bouts of insanity, he told us that the whole complex had been invaded by alien creatures known as mi-go, and that they were trying to open a portal to bring their god to this world.
We had to stop them!
As we continued, we found a powerful weapon. It was a mace, whose head was shaped like four ravens. The weapon - which was called the Ravens Head, was a powerful weapon against undead. Ichabod happily took it and looked forward to the chance to use it in battle.
Finally we pushed our way through another glass wall and entered the dome we had seen from outside. There were several long, spindly creatures with wings and tentacles, standing around a table, on which was strapped the dark rider we had been looking for.
The creatures - the mi-go we had been told of - attacked, but they were soon defeated. We went to free the dark rider, but he began to convulse on the table. Skalif grabbed him and teleported to the other side of the room, but it was too late. With a scream, the dark rider exploded, revealing a tentacled creature within him that grew very quickly to a huge size.
We began attacking it, but it was incredibly powerful, and we were hardly scratching it. The paladins then had an idea. Ichabod ordered us to retreat back through the glass wall. As we did, Ellavorn donned her water breathing helmet, raised her pistol, and fired at the glass of the dome. There was a crack. Then another. And then the glass gave in, and the sea rushed in to the dome. The creature flailed around in the water and was quickly crushed by the sheer weight of the water.
Hastily, we made our way back to the waiting submersible. The glass wall between the dome and the caves began to crack, and water was starting to seep in. We had to escape before the whole complex was flooded.
We got back to the submersible and began our slow ascent to the surface. In the darkness we could make out an enormous shape that seemed to be all tentacles and goat hooves. The aliens' god had partially manifested itself here, but with the killing of its offspring, it had no more hold on this world, so it had no choice but to return to its realm beyond the stars.
Once back on the surface, we watched as objects from the caves floated to the surface. Among them was the remains of the dark rider's clothes. In the pocket we found a letter that said that he was to get the Raven Head from Illmarsh and join his colleague in Caliphas.
So, we bid farewell to Horace and headed for Caliphas, the capital city of Ustalav.