I was out for this one, but my friend Silvercat was kind enough to take game notes; for the sake of consistency and easy access, I'm adding them to the collection here.
We leave the library with our new friend in tow. We recap - we don't need the soulgem before we fight the dracolich, but we'll need it to destroy it completely. Thelmor points out that he isn't actually a native of the material plane, but we can't figure out if that means he could poof off with the soulgem.
We head for the last room we haven't explored. Nil listens at the door and doesn't hear anything from inside. Snow sneaks in. The room is a large open space, except for five foot platforms. The light strip from the main room cuts off in the hallway, so its completely dark. On each of the platform is a high detailed stone figure of a lying gnome. Each one is different. Snow thinks they might be death memorials on tombs. There's about 20 of them.
In the walls are a bunch of blocks with handles and etched writing that Snow can't read - probably Gnomish. On the back wall there are a couple of the rectangle columns and a small alcove with a statue of a Wizard holding a staff with a dragon twisting around it and a draconic writing on his robe.
Snow comes out to tell us about.
We're thinking it's a catacomb.
Nil is annoyed that knowledge clerics don't have comprehend languages. Jhuni, however, does as well as speaking draconic. Nine and Fifteen stay in the back. Nil and Jhuni go first. Jhuni tosses in a lit ball bearing to see if anything will attack it. The new shadows are creepier than they were. We can now see that the statues are dark stone. The statue on the back glints with gold and its dragon staff is holding a black gem.
We all are immediately suspicious of the gem. On the back wall is inscribed in Draconic: Eternal Rest for Followers of Keraptis.
Jhuni casts Comprehend Languages to read the Gnomish on the other walls. It's a list of Gnome names and epitaphs. Each dais has a fancier epitaph and names with titles. Nil casts Detect Magic. The statue is covered in conjuration magic.
Jhuni asks Fifteen if it knows anything. The statues are past masters - some it knew, some it didn't. The big statue isn't a gnome. We remember we saw him in a vision - it's Keraptis. We decide to go through the drawers.
Snow can tell if there are any undead within a mile. There are. It's not a very precise spell.
Jhuni tells Fifteen to stay outside in case something bad happens. Snow uses her disguise to look like Keraptis. Honey keeps lookout while everyone else starts opening a drawer. A mechanical beetle flies out of each one. Inside are bones and personal items.
The beetles attack us. Snow stabs one and destroys it. The next one is hurt, but not down. Thelmor slashes one with Wave and then stabs it. It dies. Sunrise stabs one with her rapier and gives Snow a bardic inspiration. Perfect hits the one Snow damaged and it falls to pieces. Nil pulls out a jar and commands one of the beetles to go inside. The last one goes after Snow and bites her with poison. Jhuni firebolts it and it explodes in Snows face.
There are 144 drawers. Nil thinks if there are bodies in the drawers they're more vulnerable to looters and so less likely to have the soulgem. We want to switch to destroying the statue. Whelm doesn't want to destroy it because it's pretty, but the other weapons want to fuck it up. Jhuni promises to mend it afterward. Jhuni grabs the stone with Mage Hand. She feels something like a spell powering up and everybody hears something in a strange language (gnomish), which Jhuni can translate: "To those who disturb our eternal rest, May your ears bleed from our screams of rage."
We back out of the room and Jhuni fireballs the statue. Horrible noises start and a pink blob thing appears. Nil figures out it's a Gibbering Mouther. We decide to destroy it from afar, with Nine closing the door between each attack.
Sunrise throws a dagger at it, as she has no other applicable ranged attacks. It doesn't do much. Snow's got nothing. Jhuni, naturally, Fireballs it. Thelmor shoots it with two crossbow shots. The monster tries to run at us, but its slow and we're far away. But we hear something else happen - there's buzzing getting louder and louder from drawers that were blasted open.
Nil reads its thoughts, but isn't happy about it. It's thousands and thousands of voices - it wants to be more. Nil suggests that it not attack us or approach us. Sunrise and Snow can't do anything. Jhuni fireballs the monster and kills it along with a few of the beetles, moves up, and fireballs a swarm. The buzz doesn't lessen - the beetles apparently don't mind fire.
Thelmor moves up and shoots the swarm. One swarm surrounds Jhuni but doesn't do anything. The other attacks Thelmor, biting and poisoning him. Nil moves up and calls a Guardian of Faith. Nine runs forward and attacks the swarm surrounding Jhuni. He squashes a ton of them.
Sunrise comes in, but can't get close enough. Snow runs in, provokes the swarm by Jhuni which misses, and casts Hunter Mark on the swarm by Thelmor, before stabbing it a bunch, and then moves away. Jhuni fires a witch bolt at the swarm around her and takes out some. "Ha! That's how it's supposed to work, you bastards!" Thelmor stabs the swarm around him, then teleports next to Nil. Nil's Guardian smacks the heck out of the swarm. The swarm tries to attack the Guardian, which, naturally, doesn't work.
Perfect tells Nine to get them. Nine misses. Nil puts the heal on Thelmor. Nine smacks the beetles again and misses again. Sunrise moves up, stabs them, and retreats again. Snow stabs them some more. The swarm is starting to thin out. Jhuni shocks the swarm with Witch Bolt again until the last one falls out of the air. Thelmor turns his flames to electricity, cattle prods the swarm, and it drops dead.
We avoid the goo remaining from the mouther. The hands of the statue have fallen off. The crystal in the staff has changed to a translucent gem. Nil detects magic on the gem - it's nonmagical now. Nil heals everyone up before taking apart the statue with Whelm wile the others go through the open drawers. There's nothing in the statue. In the drawers, we find 105 gold. Nine went through the taller drawers and found a circlet made of electrum. Nil checks it and says "the only magic in this circlet is the magic of imagination." Fifteen doesn't finds some parchments and books and stashes them in it.
We net and destroy the beetles in the remaining drawers. Nil commands one into a jar so Perfect can have it. We find a bunch of copper coins totalling 33 gold. We go to rest in the hot springs room - Snow protests at the idea of bathing in water. While they're resting, Jhuni makes necklaces out of the beetle remains for Nine and Fifteen. Nil inspects the beetle they caught. One of them starts ringing like an alarm clock and slowly transforms into a spider similar, but not the same as before. It has metal wire instead of thread and looks like it's made for jumping - a spider thief.