The choice seems to be making a beeline for the pit. Pass the orange signs, pass the unusual sights, and pass the chests of certain death loot they go, all the way to the stairs.
CRACK
It was close, but somehow the group managed to press against the walls quick enough to arrest their sudden movement downward. Even Berid and Ptembridge stopped in time, though to be fair they were traveling in the back in their zombie-like state. No one will die tonight it seems. You can take your time getting down the new hazardous terrain without any rolls, and continue the path lower.
There is a small room mid-way, with large iron cages and a few bones scattered about. Another orange sign is here, but this one is defaced and scribbled out in dirt. "T*** **ck, *** **ace. ***e Fa***."
Further down. You finally spot a door at the end of the stairs, and several more defaced orange signs along the walls. The door has been inscribed with the same symbol that Drosselmeyer keeps around his neck. After a moment of peering around to make sure nothing unexpected has occurred, Drossel tapped the wall in a few places, accompanied by soft clicks. Traps. Dozens of traps apparently, which he got around to disabling one by one. There was on the roof. One under Axejack's foot, fortunately un-activated. Several by the wall. One along the edge of the door. Poison over here of course. Is that a bear trap?
"Alright. We can enter."
He pushed the door open, and the Pit was revealed.
A high ceiling arced over this room, on which dozens of large iron cages hung suspended over a rather vast area. This place wasn't build like the rest of the mansion, but was instead carved from the very rock itself. Along the walls lie a multitude of magical, alchemical, and scientific equipment, and on the far wall was a table which a bloody pile of rags were piled in a vaguely humanoid shape. Near the entrance was another corpse, long picked clean and nothing more than a humanoid skeleton with far, far too many arms to be human at all. More crude markings were made around this particular corpse.
And of course, the most important part of the room, the thing which dominated the center and gave it the name. There was a hole in the ground, seemingly punched through, which descended deep deep below with no end in sight. It was unmistakably a hole to the underdark, not unlike when you fought "Blueberry". The walls of the pit were lined with faintly glowing purple magicite. It was the dangerous, radioactive kind. You're safe for now, but extended exposure may result in health risks. Just before the pit, a crude throne made of trash and metal was constructed, and upon its seat a strange helmet which looks like it would cover the eyes. On its large cylinder-like forehead was a single glowing red crystal. The helmet is dented, it may have been damaged at some point. A multitude of wires and tubes emit from its back, hooking into the crude metal throne.
"Our Holy Artifact." Drossel approached the throne respectfully and bowed. You heard the faint shuffle of rats moving within the walls and above, apparently on the supports that the iron cages hung from.
"We have arrived. I have instructed others to provoke the devil so that he may pursue us here. Soon, we'll achieve victory. You will see."