The tunnel opens up into another large cave system.
The party will encounter three Shadow Elves. They are on patrol.
Once this Shadow Elf community was vibrant, well. As vibrant as these elves ever get. But a thousand years of exposure to the Vampire Queen's evil and the necrotic forces here (not to mention what strange radiations are coming from the ship above) have reduced their numbers and made the remaining elves slightly better than ghouls. Their alignment is now Chaotic (Evil).
They will attempt to talk to the party, but on the first sign of advantage, they will attack.
In addition to treasure they have food (more of the good mushrooms) and wine.
Note: Dwarves will notice that these passages are steadily going down.