This isn't an adventuring party. It's a suicide cult!

The Imperials were four Empire Soldiers, two Empire Archers, one Mage Officer (transmuter, CL7), and an Imperial Slayer. That was a good fight, it hurt the PCs and frustrated them when the NPCs used decent tactics and tried a fighting retreat behind a shield wall in a 10 foot wide corridor. There was no taking of prisoners, quarter was not offered and captives for questioning were apparently unimportant. They looted the kitchen like good food was major magic items (I do play up the yuck of weak mushroom beer and greasy fried lizard meat), grabbed a batch of coded messages (DC15 Decipher Script or a coerced captive, they had neither), and found the booby-trapped crystal ball. They didn't actually bother to inspect or fool with anything, just loot-and-go. During the fight the ninja had gone Ethereal in the hideout. Because I revamped the planes (and provided detailed info the the go-ethereal guy on this exact matter) the Ethereal is no longer a LOL-imma-ghost thing, it's now a real distince plane of existence. Because the hideout was less than 200 years old it didn't exist on the Ethereal plane, the ninja had just plane shifted into a solid rock. He only took about 4d6 damage.

After a short trip to drop off the coded messages at Fort Emerald** they headed back up past the trenches, around the Slith Fortifications, and down the east branch of the tunnel. When they found the beach of the southern slith lake it was "Oh carp, not more swimming." Then they spied the supply depot. This is where supplies and troops from the Slith Castle come to on barges before going to the war. The warforged artificer simply walked down alone and started talking to the slith. This was a novelty as the last time the slith had any records of a warforged was during the First Expedition and those warforged were with humans and never spoke, they just fought under human command. So the slith wrote them off as just another type of golem. Anyway the slith casters and officers had a nice hour long chat with the warforged, during which the rogue and ninja stole a barge. If they had stolen a small boat or tried to swim Phantom Mounts again they would have met several giant catfish (huge shark stats).

Their boat trip mostly followed the south wall and the found the swamp. By forgetting to write down the directions they had received they wandered the swamp for a day and a half before finding the Crypt of Drath. Now when Solberg sent the message telling our "heroes" where to find the lich he also mentioned that Drath was a nasty Imperial high mage and they needed to be careful. The artificer, dating from the First Expedition, remembered Drath and that he experimented with custom necromancy. Drath managed to apple the Vampire Spawn template to eagles, the Wight or Ghast templates to Owlbears, and was working on undead elementals. Because the First Expedition lost so many powerful magic items (and was an enormously embarrassing fiasco) people are very interested in it, especially adventurers and mages. Mages run all the libraries and almost all of the sages in towns are spellcasting ex-adventurers. Plus there's a mural in the entryway of the Tower of the Magi depicting famous moments in the history of magic, Drath is in that painting. So any research would turn up that Drath was an Enchanter who practiced necromancy as a hobby, summoned demons, and always had at least two golems for bodyguards.

Our woefully unprepared and unsuspecting party just walked into the entryway and sent the rogue and ninja scouting in different directions. While the rogue strolled past the two sealed crypts with specters in them and returned safely the ninja found the sealed crypt with the vampire slith warrior in it. He went Ethereal to try to bypass the door and ended up in solid rock again. This time the nearest open space on the Ethereal was back in the entryway, 80 feet away. 16d6 killed him as he was pushed face first through solid rock and the rock didn't break. Eventually the party realized that the horrible mess that materialized in their midst was the ninja and decided not to screw with the crypts, because they're obviously trapped. This brought them to the dark pit (80' across, dripping water, no discernible ceiling of floor) with a wet 3 foot wide stone bridge across it. While everyone else was arguing the psychic warrior started walking across it.

We left off there because some of us had to work the next day. It is November 2nd and a Living Spell Scintillating Pattern is about to drop onto him. The pit drops him 300 feet into the dark lake with an Evolved Vampire Giant Octopus in it. Yeah, totally unprepared. They just had issues dealing with some half optimized defensive mooks five levels lower than they were, more deaders a-coming.

** Remember that the secret Blades of Exile sent the PCs to the Empire hideout because they already knew that there were Imperial agents there and wanted to know where they were coming from and what they were doing. King Micah and the Exile government are busy fighting a war with the slith. It's stalemate for now, but Fort Dranlon will fall about two weeks after Grah-Hoth is released from his prison. That will open Cotra(fish), Silvar(wood), and Almaria(route to everything not in the Great Cave with the Castle) to attacks as well as threatening the trade from Formello(food) and Fort Draco(65% of all metal in Exile). Exile will have to drain all spare resources to secure the new front in the war. Plus Fort Remote will be razed by demons too. In short Exile will be far too busy to do anything about Imperial infiltrators beyond basic spy checking and anti-sabotage measures. In short the players just gave the Ark of the Covenant to the U.S. government.