Cthulhu Alamo

In the year 1050 in the mining community of Blackwell, the miners dug too greedily, and too deep. They came across a glowing stone that was, unbeknownst to them, an artifact of Y'xuthog, The Fathomless, and removed it from the mine. It was entrusted to some local "mine guards" to determine what it was and if it could be turned for a profit. These guards were Maximus Watley, Fargrin Pinkerton, Steve, and Susan.
The stone was taken to the local wise man, Estaphanos the Smart. Estaphanos ran some tests on the artifact, and was nearly killed when his attempt to drill into it unleashed ethereal tentacles that began strangling him. He survived the attempt but his mind was broken. He declared he saw "HIM" and when pressed on the issue he gave up the name Y'xuthog, The Fathomless. After that he declared he was leaving the village and marched straight off to the docks. It was the last anyone ever saw of Estaphanos.
Proceeding now with caution, the party took the artifact to the village elder, Grandpa Theobold. They told grandpa what happened and the name was familiar to him. He found an old book titled the "Cultic Mythos" and found the poem written about Y'xuthog, The Fathomless by Aquilius X'nt.
Seeing the danger this rock presented, they called for Heinrich the Tall, the mine warden. The party informed him that they should get the miners out, and be very careful moving forward. Heinrich disagreed and licked the rock to show there was nothing to be worried about. He then began to bleed out of every orifice while his flesh melted off of his body.
With the mine warden dead the party took control over the situation and began attempting to put together an evacuation plan. Grandpa told them that Estaphanos usually coordinated that, so they returned to Estaphanos' home to try and find out when the next ship would be coming. They managed to find a sending stone that was linked to one Captain Neville. The Captain informed them the soonest he could make port was 3 days time. The party thanked him and continued their plans to fortify the town from the unknown threat until they could get the peasants out.
Their next stop for the evening was to go check out the church and evaluate if it would be a good location to fortify. Steve spoke to the preacher, Father Abbles hoping to get a better understanding of the situation in town. When Steve spoke the name Y'xuthog, The Fathomless, Abbles advised him not to speak it's name, for fear of giving it strength. It was decided the new name would be Mister Hogg, or Boss Hog if you like. Though that added some levity to a tense situation, Steve could tell something was off in the church. He discovered only the single Altar of Mystra, Goddess of Magic was still consecrated. He accosted the Father, demanding the truth, and Father Abbles began to change. His flesh started to rot and in the midst of him opened a tear in the material plane, through which saltwater poured out as he shifted into a horrible mass of flesh, eyes, and tentacles. The party put the abomination down, cleaned up the mess and found the mad priest's diary in his bedroom. It spoke of the Ruins of Gelagosa before the cohesion broke down into unintelligible scribbles.
They rested for the night, with a plan to inform the coastal areas of the need to evacuate in the morning. Reaching the Docks first, they found Estaphanos' clothes on the edge of the dock with no sign of the man. Susan went to ask the birds if they'd seen him when she was attacked by a Kraken. The party beat the beast back, and it fled back away from the coastline. Moving south along the coast, they reached Fisherman's Jashnu's House, only to find it flooded with saltwater, with the bloated corpse of Jashnu inside. Their next stop was to the Dragonsbreath Mine, which they found entirely devoid of miners. After seeing some apparitions at the mouth of the mine, it was decided to collapse it for the safety of the community. By this time it was reaching evening and the party returned back to Blackwell.
That night, they gathered all the peasants to the mine walls to try and keep everyone safe for the night. This did not work, as the town flooded and the peasants were accosted by ethereal tentacles, which stole many of them away to the dark waters of the night. The party tried to destroy the artifact and the room it was in deep in the mine to try and rob Boss Hogg of his prize. It didn't work, and the remaining peasants had to tough out the night. It was decided they would move north at daybreak to reach higher ground.
When the dawn came and the waters lowered all survivors moved north, first to Butcher Grogshanks, then to the Ruins of Gelagosa. Butcher Grogshanks was amicable, he agreed to come along, with all his food for the peasants, and fight whatever may try to destroy his home. When the ruins were on the horizon, the largest building appeared to be some sort of chapel. Once it was reached and the building investigated it was found to be a temple dedicated to the worship of Und Tralla the Immortal. They found access to the catacombs, and in the catacombs, they found a vampire sleeping in his coffin. Awakening him, they found him to be Victor Le-Massapeaux, an original resident of the ruins who ran from Boss Hogg's wrath to his coffin when the Boss Hogg destroyed Gelagosa some 600 years ago.
Victor offered a way to try and stop Y'xuthog, The Fathomless, by defiling his artifact and defeating him in a physical form. The vampire was sent to get the stone, and they moved the peasants into the catacombs for safety, as they were still consecrated to Und. When Victor returned with the stone, everyone took their places, and the stone was pissed on, properly desecrating it. This caused the storm outside to swell, and a torrent of saltwater burst the chapel door open as the room began to flood. A servant of the Boss Hogg came in with bloated corpses, and shortly after the Kraken from earlier arrived. Steve blew his Horn of Valhalla and summoned a dozen Berserkers of Bane to assist in the battle and the beast was slain. But once it was slain, the Avatar of Y'xuthog, The Fathomless burst into the chapel. The chapel continued to flood, and eventually Maximus Watley was lost to the murky depths. Suffering casualties, including horrid mutations, the avatar was eventually put down. The waters receded and in the morning the sun came out from the clouds, shining on the path to the docks where Captain Neville was waiting.