On the first foray it was just Finloss, a half elven fighter/thief level 1/1 (AD&D ), and his henchmen Orion, a 1st level human enchanter (3.5e). Since Chris was using Castle & Crusades plus some D&D/Hackmaster tweaks, it was not a problem the characters were from different editions.
As far as we know, there are two possible entrances to "The Core", a main entrance through a temple and a "backdoor" through a lava chute. We decided to take the last one. This natural chute went down and deep into the mountain, until it became clear it has been worked out. Doors and side corridors appeared. Ignoring a door on the left of the main tunnel, we took a side corridor to the right until we reached a door. Finloss listened and heard voices on the other side. Anticipating trouble Orion casted Mage Armor on himself. Then Finloss yanked the door open and surprised 3 humans playing cards and drinking around a table. Orion casted Sleep and they fell into a deep slumber. They were quickly stripped of armor, weapons and other possessions, then tied and gagged. They are bore a symbol resembling fangs which identified a demonic cult responsible for several attacks and disappearances in the surrounding area. That was enough reason to slain them in their sleep.
A door led to another room which contained the beds and trunks of the guards. We rummaged through their belongings taking any valuable. Another door opened into a more lavishly furnished room. A stand with a book and a padlocked trunk stood out. Finloss easyly opened the lock but suspecting the trunk trapped, opened it carefully and a dart shot from inside, missing him. In the trunk he found a couple of potions, a silver circlet wrappend in cloth, and a pouch of coins. Orion inspected the book which resulted to be a spellbook! We grabbed all these things and before leaving spiked a door that exited the room with a dagger. We took the bundles with armor and weapons from the guards and quickly left the place.
On our way out we encountered some strange red round creatures, two feet wide, several eyes, a pair of appendages they used to crawl, and a maw full of pointy teeth. When they closed to melee Orion casted Burning Hands and they exploded damaging both Finloss and Orion. The pair of adventurers now badly wounded rushed out of the dungeons praying they didn't encounter anyone on their way back to town.
They reached the nearby town safely, and spent several days healing their wounds, and selling and inspecting their loot. The spellbook had wizard spells Sleep, Identify, Tenser Floating Disc, Jump and Magic Missile. The next day he casted Identify on the circlet, which resulted to be a Circlet of Persuasion. The potions were of Cure Light Wounds and Invisibility. After that they were ready for a second incursion.
This time they were joined by a redheaded elven 4th level fighter named Etan. The trio went again into the dungeons through the "backdoor" entrance. They went to the same place they've been on the previous foray. Finloss listened at the door and heard voices. Orion sent his rat under the door but it came back scurrying, so the party left and went back to the main tunnel.
The tunnel widened like a funnel with corridors that opened left and right. They checked the first on the left. It went straight and led to two sets of double doors. Theone on the right were of polished metal with no hinges or handles. The one on the left were wooden and richly carved. These opened into a huge domed amphitheater. We descended the terraces and upon reaching what would be the stage level Finloss found a secret door. He crawled into a tight space and came behind the curtain into a place full of ropes, pulleys and counterweights and two one-way secret doors opened back into the amphitheater.
Back in the main corridor, the party explored the next passage on the left. It led to an octagonal room with a big diamond in the center. Everyone smelled trap and left the diamond alone, but searched the room finding two secret doors. Exploring one of them, they found a corridor that had two doors at the end. One room was empty, but in the other 6 skeletons were guarding 3 teak wood trunks, so combat ensued. The undead were soon but a pile of bones, and the party dragged the trunks full of silver to the main passage.
They were at it when up ahead, a couple of hobgoblins emerged from the wall! They commanded the party to surrender but Etan ignored and tauntingly turned her back on them. The hobs took the bait and charged. Etan turned and fired a couple of arrows at them. On fell on the spot and the other, wounded, turned to flee. Another arrow flew and the creature fell. Upon inspection the group found they were carrying a sealed bag with coins. The seal bore the fangs of the cult. It was then that Finloss came with a plan: impersonate the hobgoblins and take the bag to the guards to catch them off-guard.
So they did, and when the guards opened, Orion casted Sleep on them. This time all fell except one, so Etan fired an arrow at him, hitting, and Finloss charged with his spear, missing. The guard took his mace and attacked Finloss hitting him really hard. Etan interposed between them and attacked the guard, almost killing him. He surrendered, so they bound and gagged him. They then stripped all of weapons, armor and possessions, and killed the sleeping guards. Finloss drank the Potion of Cure Light Wounds, and the group left dragging the trunks behind.
Once in town they delivered the prisoner, a cleric of the cult, to the authorities and claimed the reward. Inspecting all the loot, the bracelet and spear were magic, a Bracelet of Shadows (+2 AC) and a Spear of Pinning.