They immediately opened the doors leading to room with a massive fiendish couatl statue with a podium in front of it. The walls of the room were mirrors that reflected everything the PCs did but sometimes it seemed to reflect a bit more as if it was connected to another plane. The podium itself was very basic and made of wood. The dagger however was far more impressive, it was made a massive snake fang and etched with runes. As the PCs entered the room the statue said "Show me your mortality" backwards. The PCs searched the entire room, checking every mirror, every tile, hoping for a way to move beyond the room but to no avail. Eventually they sat down and figured out what I said (I didn't give them any hints so they had to sound it out). One eventually stepped up and stabbed himself with dagger. His body faded away in an instant disintegrating in front of them. The PCs of course freaked out and I pulled the PC aside and told him what was going on. A few moments of debating later the rest of the part took the plunge. They all found themselves in the ethereal plane and the statue of the couatl had disappeared in its place was a tunnel that lead to another room with cyclops like fountain. Before the party could investigate the fountain two strange ghosts emerged from the mists of the ethereal plane and attacked the party obviously upset at living souls invading the ethereal plane (the PCs weren't dead the statue just forced them into the ethereal plane version of the ziggurat). The ghosts not having a deflection bonus to ac meant they dropped like a sack of potatoes. The PCs investigated the fountain and found runes inscribed on it that said "Fountain of Rebirth". The same PC that stabbed himself decided to wash himself in the waters and returned to the material plane. Again the party followed his lead and they moved into the central Chamber.
This room contained a staircase that required a magical key of some sort to get out. After fidgeting with the lock for a bit the PCs looked through the books on the shelves but didn't notice the secret door behind the one on the right and continued to the forest room. The ceiling of this room was unique in the fact that it was like a two-way mirror. You could see outside and let sunlight in but from the outside it looked like carved sandstone. In the room itself there was a massive snake that I affectionately named Seirozach. Seirozach was a normal CR 2 constrictor snake that I made into a huge sized monstrosity. My PCs gave me dirty looks after they discovered the snake and for good reason. Seirozach after grappling a person could inflict massive damage. But his hp pool although large was no match for the damage the pcs could inflict. By the second round Seirozach was already dead and one of the PCs was heavily wounded and the fight wasn't over. From the north ran a lizardfolk druid who was upset with the loss of his pet. He attempted to entangle the PCs but was only able to get the groups "tank" (He was playing 3pp class that was sort of like a paladin). The rest bum rushed him and learned that he was far deadlier in melee than at range. He flailed with tooth and nail inflicting small amounts of damage to different party numbers. He too died with a whimper but the overall combat between him and Seirozach drained the party quite a bit and they took a bit to recover using healing items and wands.
They explored his library finding a number of interesting items. They obtained a number of interesting books, alchemical items, and a leshy vial that had already been completed. The next room was another conference room. This one was lavishly decorated with with a beautiful carpet, masterfullly made darkwood gold-etched table, and enough drinks to keep a full bar of angry irishmen happy. Hanging from a chandelier was a strange featherless bird with tentacles spewing from its mouth. The creature dived at the party with surprising accuracy leaving a nasty bleeding gash in the parties gunslinger. It tried to fly back up to the chandelier so it could dive again but was taken out of the air by a well-placed bullet.
The next room was a bedchamber that was pristinely clean. Food, drink, and entertainment as well as hunting trophies littered the room. The pcs took anything of value they could carry and opened the door to the south. They were greeted by floors of etched gold covered by a red and black carpet that lead to another room to the south. Statues and hunting trophies lined the walls, in the center of the room on the left wall a fireplace roared, in front of it a set of four chairs surrounded a small table with a delectable looking seafood dish sitting upon it. Across from the fireplace on the right wall was a large cage that contained what looked to be a snake that looked like a much smaller Seirozach. When the pcs walked into the room an annoyed looking serpentfolk covered in lavish green and gold robe looked over at them. Across from him in the opposite chairs were two human women with scaly skin known as Coil Cultists. A fight broke out immediately and the serpentfolk cast a bunch of defensive spells why the party was tied up with the coil cultists. The cultist had thrown smoke bombs at the PCs and tried to use hit and run tactics inside the cloud of smoke but found the pcs too much to handle but lasted long enough for the priest-in-training to complete his spell routine. He joined the fray with dagger and fang trying to wear his opponents down with his nasty poison but to no avail. The PCs felled him quickly by rolling well and ignoring his mirror image clones.
The PCs proceeded to raid his room in hopes of finding the merchant they cut through the ziggurat to find but no luck. They seemed confused that the merchant wasn't here. After a small conversation between PCs they decided to loot the room and then go talk to the hybrid lizard/serpentfolk they had met earlier. Perhaps he would know where the merchant was. The party found a marilith's skull carved into a helmet and rather than wanting to sell it they fought over who should have it. After a few minutes of debating over the helmet they met with the hybrid again who to their surprise had the merchant tied up. They told the hybrid they had honored their side of the deal and to release the merchant so they could leave. The slizardfolk agreed to let him go as long as the PCs didn't return to the ziggurat. The PCs "agreed" again but as soon as the merchant left the room they turned around and attacked. The hybrid never saw it coming (bluff checks too stronk) and was placed upon the mountain of corpses the PCs to made.