So, I've got the 1st level adventure, and I've got the 3rd level adventure. Now I need to connect them by filling in the 2nd level adventure. I look at how the first adventure ends (an arboreal has killed a duergar from the Wastingdeep Mine, the scholar Gendal is kidnapped) and how the third adventure begins (upon returning to Fallinghollow with Gendal, stuff happens) and see that the second adventure is about rescuing Gendal from duergars. That seems like a dungeon crawl to me, and having the occasional back-to-the-roots dungeon-crawl adventure is fun.
The greatest danger in a dungeon crawl adventure is that it'll be dull and non-linear. You mix this up by having interesting NPCs the heroes can talk to, hints of mysteries to come, and several decision points while they're in the dungeon.
So here's what I came up with for this:
Chapter 2: Descent into Wastingdeep (2nd level)
The heroes return to Fallinghollow to meet with the scholar Gendal, but he’s been kidnapped along with other residents. Signs point to the nearby Wastingdeep Mine. The heroes learn that the iron mine connects to a larger dungeon occupied by duergar slavers. The heroes must vanquish the duergar and the barbazu devil who commands them.
Part 1: Wastingdeep Mine
The heroes confirm that Gendal has been kidnapped, although no one saw any kidnappers as duergar can become invisible. His house has signs of a struggle and two broken and discarded bola bolts; a successful DC 16 Society check reveals they’re the kind duergar sharpshooters use. Heroes asking around can learn Wastingdeep Mine was an iron mine abandoned when some bad gas flooded parts of it. The gas is invisible and odorless, and therefore the mine was deemed too dangerous to keep using.
Encounter 1a (Moderate 2)
Recent tracks lead in and out of Wastingdeep Mine. Two earth mephitsand a sewer oozeguard the narrow passage near the mine entrance at the command of the duergars. They’re near an alcove with dusty mine storage equipment, including a forgotten +1 pick.
Encounter 1b (Moderate 2)
The duergar loosed a lumbering giant stag beetleinto the mine corridors; it isn’t affected by the bad gas. This beast meets up with the heroes before they can explore very much of the mines.
Encounter 1c
Navigating the maze-like mine requires a lead hero make three DC 16 Survival checks, each taking an hour. After three successes, the party makes their way to the bug yard in Part 2. They can return to the surface at any time by retracing their steps, but this reduces their earned successes to zero and they must start again. Each failure takes the heroes to a pocket of bad gas, making them enfeebled 1 for 24 hours (which stacks, up to enfeebled 4). On a critical failure, the heroes also inadvertently return to the start, losing any progress made. On a critical success, the heroes spot a side passage with a boarded-up mine office. This office contains a map of the entire mine, allowing the heroes to traverse it automatically and further gain direct access to any of the three areas in Part 2: the bug yard, the slagyard, or the fungus cliff.
Part 2: Duergar Support
The upper level of the duergar caverns, below Wastingdeep Mine, contains three different chambers the duergar use. This is the bug yard where the duergar train centipedes, the slagyard where they seek useful slag, and the fungus cliff where they collect food. These areas all connect to each other (and to the Iron Stronghold in Part 3) through narrow passages with a few dead-end tunnels off of them. The heroes can use these dead-end tunnels to rest safely, if they’d like, as the duergars rarely explore them. The duergar come and go through the bug yard, so this is where their tracks from the mine lead.
Encounter 2a (Moderate 2)
The entrance to the bug yard has a gate made of thick wire that the yard’s captive centipedes have just realized they can break open. Two giant centipedes attack the heroes immediately, with 2 more joining each round until all six giant centipedesattack.
Encounter 2b (Moderate 2)
Deeper in the bug yard—which connects to the rest of the duergar caverns—two duergar sharpshootersare training three giant centipedes. They all attack the intruders from the surface. A nearby chest with metal whips and other training gear contains a lesser antidote and a lesser healing potion.
Encounter 2c (Moderate 2)
The fungus cliff is a deep crevasse where tasteless but nourishing mushrooms grow in a surprising profusion. The mushrooms provide cover. Here, a duergar taskmaster is training two duergar sharpshooters in shooting long distances off the edge of the crevasse. They fight as soon as they notice the heroes. The duergar taskmaster has a heavy iron key (to the Iron Gate in Part 3). A mushroom-gathering basket has a few dried, nasty mushrooms and a potency crystalin it.
Encounter 2d (Severe 2)
The slagyard is where the lava plume that broke through the mine’s lower levels—and released the bad gas that still fills part of the mine—melted a bunch of iron into slag. The duergar sometimes pick through it for useful iron slag. There’s currently a duergar taskmasterhere talking with a faceless stalkerwho’s masquerading as the scribe Gendal. Unless the heroes are noisy when they approach, they overhear the pair talking about how the faceless stalker can best impersonate Gendal, return to the surface, and collect information about weaknesses of the fey and arboreals. This is a clue that the duergars (and their devil masters) aren’t truly allied with the arboreals. When this pair discovers the heroes, the taskmaster fights while “Gendal” pretends to be in trouble long enough to get close to the heroes for a surprise attack. The duergar taskmaster has a heavy iron key (to the Iron Gate in Part 3). The faceless stalker has a shoulder bag containing a large vial of its blood (which functions as two doses of infiltrator’s elixir).
Part 3: The Iron Stronghold
The lowest level of caverns claimed by the duergar are all one reinforced fortress.
Encounter 3a (Moderate 2)
The Iron Stronghold’s entry is guarded by two duergar sharpshootersand a duergar taskmaster. The taskmaster has one of three keys to the Iron Gate.
Encounter 3b
The Iron Gate leading into the fortress requires 3 keys: one held by each of the three duergar taskmasters outside the fortress. The lock is treated as a good lock if the heroes have no keys, an average lock with one, a simple lock with two, and it unlocks with all three.
Encounter 3c (Moderate 2)
The large hall beyond the Iron Gate is set up with several mushroom-stuffed leather sacks to resemble humans. Three duergar bombardierspractice hurling bombs here. Several rooms of the fortress lead off of this hall. A small table bears a moderate alchemist’s fire and a crafter’s eyepiece.
Encounter 3d (Moderate 2)
The fortress’s armory is well stocked but guarded with a spinning blade pillartrap. It contains three tower shields, six dwarven waraxes, six mauls, four suits of splint mail, and a retribution axe.
Encounter 3e (Moderate 2)
The forge is where all the duergar must labor in shifts, but currently two duergar bombardiersand a duergar sharpshooter are here. The bombardiers are bullying the sharpshooter into doing their work, and she’s frustrated with that. If a fight breaks out, the duergars all fight initially, but the sharpshooter turns against the bombardiers if given the opportunity. In exchange for her freedom, she tells the heroes the layout of the stronghold. A suit of full plate and an ingot of silver worth 25 gp are here in the forge.
Encounter 3f
The barracks in the fortress aren’t regularly inhabited, but duergar elsewhere retire here if the heroes wait. The only trunk not filled with mundane clothes and tools has an onyx worth 10 gp in it.
Encounter 3g (Moderate 2)
Four duergar sharpshootersare planning a raid on the surface for slaves. Their leader, the barbazu Gresshix, wouldn’t approve of an unsanctioned raid, so they’re being very covert about it and attack anyone who disturbs them.
Encounter 3h (Severe 2)
The prison of the Iron Stronghold contains only one living prisoner currently: the actual Gendal. A barbazudevil named Gresshix is keeping him here until he receives word from his superiors in a distant town Gresshix has been careful not to name in his prisoner’s presence. Gresshix has the key to the cells; trying to open Gendal’s cell door without it triggers an electric latch runetrap. Another cell here contains a skeleton with an onyx dog wondrous figurineamid its bones; this unfortunate prisoner swallowed the figurine to use it later, but died with it in his belly.
Conclusion
Gendal is pleased to be rescued and anxious to get back to Fallinghollow. He listened carefully to his jailer Gresshix, and got the impression that he’s associated with devils who have infiltrated one of the towns in the Northfells. Gendal plans to do some research about names Gresshix dropped to find out which town that is, but he wants to go home first.
