The Gothic Touch

(Mini-adventure, ripped whole from Karl Edward Wagner's Elric short story, The Gothic Touch, published in Tales of the White Wolf)
While travelling north to Verella, the party is struck by an intense thunderstorm. Seeking shelter from the horrible downpour, they find a ruined castle and bring their horses inside the mostly intact great hall. Once they have dried off a bit, they consider exploring the ruins. Before they can, the door opens and a man leads his horse in. He greets them warmly and introduces himself as Kane. He is a very large man, as tall as Jozan, but even bulkier with muscle. He wears an unfamiliar style of banded mail, carries a very large sword as well as a battleaxe, short sword and dagger, all cast from unknown metals, as well as many belt pouches. When they mention they were thinking of exploring, he asks them to help him, he is here to seek out a great power of corruption in catacombs below the castle. He leads them into the wine cellar and examines the wall, looking for a clue. He draws back a gauntleted fist and punches a whole in the old brick of the wall. A lever is revealed and he asks if the party is ready. He pulls the lever and a section of wall retracts and slides aside, revealing a passageway. Kane leads them into the hallway and left at the first intersection. They hear beastial shouts and something coming towards them. They are struck by a wave of degenerate, mutated beings, who might have been human once. Now they have extra or missing limbs and eyes, claws and hideous skin, a parade of creatures from a 1960's radioactive mutants movie. Kane draws his sword and axe and they wade into battle. The creatures attack without care or remorse and the party cuts them down, Kane kills as many as the adventurers combined, moving even faster than Ulayoth and striking harder than Jozan or Antonio.
Kane leads them to a stairwell and they notice the rock floors and walls have given way to all metal. Hearing more of the creatures coming up the stairs, Cyrus leans over and directs a Psionic Blast down at them. Kane pulls a small metal cylinder from his pouch and manipulates it and drops it over the edge. It cheeps like a bird as it falls and then there is a huge Fireball like blast. When the party gets to the bottom, the stairwell is scorched and blackened and mangled bits of creature are everywhere. Kane takes them down another passage and warns them they are close to the source of the corrupting power. They will be exposed to it briefly, but it should do them no permanent harm. The passageway they are walking down is now lined with strange pipes, more beasts attack, from before and behind. Jozan, Antonio and Ulayoth take the rear while Kane and Cyrus take the front. Kane and Cyrus kill their share and Kane trots ahead, leaving the others to fight a rearguard action. Cyrus follows Kane to keep an eye on him for betrayal, but Kane accepts his company willingly. Kane leads Cyrus to large room, filled with strange machines and alchemical looking glass instruments. In the center is a cracked metal pedestal, sickly green light glows from the gaps. Kane removes his backpack and opens it, inside is a large metal drum with a screw lid. He removes the lid revealing a cloth lined central cavity. He steps to the pedestal, takes off the top and reaches inside to pull out a glowing transparent cylinder which gives off the sickly light. Kane stows the cylinder in the metal container in his backpack, then screws the lid back on and dons the pack. He tells Cyrus they are done and they need to return.
Kane and Cyrus rejoin the party and Kane leads them back to the surface. Jozan questions what they do next and Kane tells him not to worry, any remaining creatures will die out now. They get back to their horses and Kane tells them they must leave the castle now; the storm is ending and they will be able to ride to a nearby town in a couple of hours. The party doesn't want to ride in the rain filled night, but Kane convinces them they have to. They mount up and ride north and true to Kane's word, the storm is ending and the clouds begin to roll away. The rain stops, the clouds move off and under the moonlight, there is no sign that the castle was ever there…The party rides on to town, shaken and disturbed by what they have experienced.