Social Interaction10
9.6Overall Score
An incredibly strong offering. Some repetitiveness in combat, but excellent exploration and social interaction opportunities.

The second part of the Waterdeep adventure series came out a little less than two weeks ago (well, for me; I shop at local game stores that all have the earlier release dates). My full disclosure on this is that I bought my copy (not a review freebie), one of the designers is a good friend of mine, and another writer is a friendly acquaintance. I won’t go easy on their chapters as a result, because I think they’d be offended if I did.


As W:DotMM is a massive 320 pages and I certainly haven’t run it, I won’t be going into great depth on any of the chapters, but you’ll get my impressions and a summary of the tone of each level. In case you missed the memo, there are a lot of levels in this here legendary megadungeon. This book details portions of 23 levels, with a separate chapter for the city of Skullport. I am going to do what I can to keep spoilers firmly contained – I’ll be name-dropping things but not providing context.

Now, I have had The Ruins of Undermountain, The Ruins of Undermountain II, Skullport, and The Lost Levels sitting on various bookshelves over the years, essentially undisturbed. I’ve read them, which is to say I skimmed them and – even at the time – retained nothing much of the text. Between you and me, adventures aren’t written to be memorable for the reader, only the user. We’ll see how this one treats me as a reviewer.

With only those 320 pages to work with, this adventure doesn’t remotely attempt to detail and populate all of the rooms from those massive maps found in The Ruins of Undermountain. Instead, it details and thematically unifies a core region of each level, and leaves open-ended tunnels toward areas of the DM’s own creation. Or, you know, a place to use pieces of TRoU’s mega-maps, if that’s your jam.

There are, in a sense, two main approaches to a dungeon like this, and the book naturally supports both to some extent. In the first, you’re living a life in Waterdeep, owning and operating the inn you received in Waterdeep: Dragon Heist. You only descend into Undermountain when you receive a mission to do so, perhaps chosen from the four starting hooks and the four follow-up hooks. In the second, you descend into the dungeon, and we’ll see if you kill Halaster before you forget what daylight looks like. (My advice: go with the first one. Dungeon fatigue is a concern at many tables.)

Now, twenty-three levels – plus, again, a small city – don’t exactly get covered in any kind of 1:1 way by eight quests. There are other through-line stories to draw you onward: most of all, the Mad Mage and his sinister apprentices. Halaster is exactly the type of villain I’ve argued in favor of for the last eight years. No matter how powerful you are, when he shows up, fighting him is not a useful answer. He has agency and propulsive force – specifically, six goals outlined in a sidebar. These goals turn the adventure into much more of a toolbox, because Halaster’s appearances, active efforts, and fallout aren’t scripted in any way.

There are also a few other potential massive story developments that provide narrative fuel – mysterious names to investigate (and the dungeon is the only source), and Alterdeep. I can’t say enough good about Alterdeep, but anything I did say would be a simply criminal spoiler.

One big note on format: this book doesn’t do boxed text. I leave it to you whether that’s a good or bad thing for your personal style. The description is often of a kind that you can read it aloud to the players, if you’ve mastered the trick of reading from a teleprompter or dungeon writeup, but it’s not boxed off to encourage that behavior.


Level 1: Dungeon Level

Character Level: 5th
Theme: Crime below street level
Normalcy and the edge of weirdness

What a perfectly quotidian yet fully encompassing name. With all of the weirdness that the dungeon is going to contain, this is where Undermountain introduces some motifs, including some of its simply unfair gotchas. On the other hand, those gotchas are now annoying and possibly embarrassing but not lethal, so the dungeon isn’t what it was in 2e.

This level has a lot of enigmas that simply don’t have a full explanation. Looking for a naturalistic explanation of each secret door and starkly empty chamber is a mistake, here and throughout Undermountain, unless the DM is ready to do a phenomenal amount of extemporizing. I would suggest that DMs lean into the decay and mixed meanings that come from centuries of reuse and many, many looting expeditions.

I’m just going to say that a lot of this level’s puzzles and oddities need spells, often 3rd-level spells, to resolve. If you come down here without at least one and preferably two 5th-level spellcasters, you’re probably going to bounce off a good number of challenges. I don’t think it’s bad, just… how can I put this. Approach this level like you’re a Cthulhu investigator: you’re obliged to work your way through the challenges so that you can start gathering the clues you’ll need later on, but you’re bleeding hit points and spell slots, and accumulating other consequences. Unless your quest puts you on a timeline for some reason, know when to bail or to leave an enigma unsolved for awhile.

My big criticism is that there are a number of things that seem like they’re rewards that are going to be useful, but turn out to be nothing. I think a lot of players would feel grumpy about holding onto a Thing for a couple of levels, waiting for its useful moment, only to discover that it was never correct or useful in any regard. It’s a hallmark of Gygaxian and Greenwoodian dungeon design (Haunted Halls of Eveningstar, you know what you did) and I’ve never understood how that serves the medium-to-long-term interests of players or DMs. It’s sort of a contra-Chekovian thing, while contending with the limits of player memory and engagement.

This level has a real strong use of encounters that will include some amount of conversation, whether or not there’s also a fight. That’s great to see. A lot of the fights that are only going to be fights are solitary creatures – a pretty questionable decision in 5e, even in a party of just 4 players.


Level 2: Arcane Chambers

Character Level: 6th
Theme: Travel junction; dark mirror of the surface
Tone: Isolation

This level includes a lot of payoffs for the smaller stories that got seeded in Level 1. I like that there’s a mix of short stories, medium-length stories, and then the stories that cover the whole dungeon.

I still see a lot of rooms that leave me wondering what the point of that room was – what it was trying to get across about the dungeon or its inhabitants. Too many encounters involve convincing the players they’ve found a puzzle to solve, connecting what seem like a lock and a key, and finally revealing that it wasn’t the least bit relevant. It’s an enormous waste, and it seems as if it’s trying to frustrate the players into no longer trying everything. Also, you spend a lot of time saving people who manifestly don’t deserve saving (but saving them is the only remotely likely way to engage with the content). Since we live in the Age of the Actual Play, I hope to see how different DMs use some of this content.

Finally, one of the centerpiece encounters of the whole level is… fine, there’s nothing wrong with it. I’m just constitutionally incapable of seeing (uh, minor spoiler) “goblin bazaar” and not turn it in a more Christina Rosetti direction. If you’ve been reading my work in Tribality for the past couple of years, you aren’t terribly surprised.


Level 3: Sargauth Level

Character Level: 7th
Theme: Underdark conflicts and piracy
Tone: Tense conflict, minimal weirdness

This is a classic competing-dungeon-factions deal. I’d expect the great majority of parties to go with the same faction, or reject both; the other faction would be untenable for almost all groups. (It’s cool if I’m wrong.) The text nudges the DM in that direction as well, with a quest for the faction I expect they’d favor, and none for the other.

The reason adventure writers and game-runners drop PCs in the midst of multi-sided conflicts is that it pushes interaction. That’s very likely to work out here as well. Okay, that, and the certainty that two parties going through the adventure will have more widely varied experiences.

Skullport is on this level and the narrative pushes the PCs to venture there as part of exploring it. It’s separate chapter, and I’ll cover it when I get to it.

There’s also an interesting approach to information distribution in the whole adventure. Instead of specifically declaring which person or book holds a given secret, you randomly determine which secret a person or thing knows at the time the players encounter it. You won’t necessarily learn the early secrets early, but as long as there are more learning opportunities than secrets, you can stack the deck in favor of the PCs learning everything they need to know.


Level 4: Twisted Caverns

Character Level: 8th
Theme: Underdark wilderness
Madness and scheming

This level is almost entirely wilderness, with only a few signs that it’s actually part of a constructed dungeon complex. On the other hand, the encounters that don’t lead anywhere except frustration are essentially gone from this level, as far as I can tell. Most of the encounters factor into the overarching story in a clear way. This seems like a very well-constructed level to me. I particularly like the super-tiny Storm King’s Thunder grace note.

At worst, there’s one little story on this level that I think is interesting if it plays out, but given the NPC’s motivations to reveal nothing to the PCs and their extremely convincing disguise, I’m not sure how the PCs would ever figure out that widget elsewhere has anything to do with anything. Even an identify gives no reason to draw a connection there. Here again, I would love to see if and how other DMs approach this. (Encounter area #4 and the thing with the thing.)


Level 5: Wyllowwood

Character Level: 8th
Theme: Forested wilderness preserve
Tone: Control

This is another level with a single primary story that touches all of the minor stories. The level has a definite boss, and her utter control over every detail of the level is Halaster writ small. There are a lot of neat ideas here, especially the device that controls a bunch of things about this level. I also like the story about the alignment change thing, though I think the Aftermath paragraph about it is one of the less-satisfying outcomes because it leans so hard into prescriptive elements of alignment. I can’t figure out how else to talk about this without getting super spoilery.

This level has a lot of great potential for interesting encounters, including one that answers one of my meta-questions about how to get information into PC hands. Other than being interesting, though, this level doesn’t seem to have any crucial information or story beats. You can use this level on its own if you just need an adventure for some 8th-level characters (even if it’s not otherwise an Undermountain campaign), or you can run some other 8th-level content in its place as your PCs progress through an Undermountain campaign. That kind of modularity is, in the balance, a positive.

As a side note, this is at least the second time that a party with one or more goblin PCs might have a super different experience, in a positive way. Just something to consider as you prepare to run or play it.


Level 6: The Lost Level

Character Level: 9th
Theme: Lost dwarfhold and Tomb
Tone: Intrusion versus Misdirection

This is a pretty direct update of the old Dungeon Crawl: The Lost Level supplement, which as it happens I have read fairly recently. Er, tried to read. After several valiant efforts, I got tired of how it made my eyes bleed and I gave up. The good news for you, dear reader, is that DotMM’s text is in a more reasonable font size and the writing is – if still an adventure – less bone-dry.

This level tells the story of a former living space, and many rooms have no puzzle, trap, or monster of any kind in them – just stuff to see and, potentially, feel some kind of way about as you proceed (also you can loot these rooms largely unopposed). My natural reaction to some of these rooms runs directly counter to success in the dungeon, though. I’d want to defeat the various intruders (other than my own party, of course) who aren’t supposed to be here, and either seal the place up again or find a dwarf clan interested in doing something with what’s there.

Look, I’ve already said that skipping levels is sometimes called for, and that’s true here too – but if there’s a dwarf of any kind in your party, you’re doing their player a significant disservice to skip this level. A duergar PC could have a completely different solution to this level, but that’s even more of a positive reason to use it.


Level 7: Maddgoth’s Castle

Character Level: 9th
Theme: Big and small
Memory loss and preservation

This is another updated adventure from the Dungeon Crawl series. I think I owned a copy, but I couldn’t put my hands on it right now. There’s not a lot of combat challenge to be found here – the main things you could find a challenge fighting strike me as more pathetic than something I’d want to kill. For 9th-level characters, the listed challenges look trivial at best.

There is interesting stuff to find and story to unfold, as you explore the castle. Much as you should be sure to play level 6 if there’s a dwarf in the party, this is a great level for a wizard to play, especially if you write them into the thing in 36a. Other than that, this would be an easy level to skip or to use in isolation. It’s not bad! It just doesn’t have a lot to do with anything. Maddgoth’s controls are another prefiguring of Halaster’s control over the dungeon, much like the Wyllowwood.


Level 8: Slitherswamp

Character Level: 10th
Theme: Frog and snake. Also, frog… and snake.

This level continues the underground-wilderness style of levels 3, 4, and 5. I don’t know that it accomplishes much in Halaster’s core story, or that of his apprentices. It does introduce some NPCs from level 9 that might help to draw PCs onward. Other than that, it feels like a progression step for XP and physical space – that is, you need to be here to descend further, because the arch gates won’t work for you yet. Increase its relevance in a quest-driven campaign by bulking up the Dendar story here.


Level 9: Dweomercore

Character Level: 10th
Theme: Complicated détente
Tone: Ruthless competition

This is one of my favorite levels so far, because it tells a lot of smaller stories about what life is like for people who can’t operate in “normal” Waterdhavian society. There’s a pretty nice mid-campaign head-fake going on here. It’s also the kind of dungeon level where the PCs walk into a complicated web of relationships and probably meet everyone before the bloodshed starts. It’s possible to get through this whole level with one fight, though that doesn’t get you much of the XP you need for the next level.

This level also has a network of pneumatic tubes. Also considering the gas lighting on an earlier level, these are increasing signs that Undermountain operates on a very different tech level other areas of the Realms, all the more so as you go deeper.

This also feels to me like a level that PCs could reasonably clear and use as a jumping-off point for later explorations. As with many levels of the dungeon, opponents are often isolated or in smaller numbers than would challenge the PCs. At least here it feels quite reasonable and likely that starting any fight attracts attention and further combatants – though it’s more of a question which side they’d join. On the gripping hand, counterspell is jaw-droppingly overpowered on this level.

I don’t recommend skipping this level, and I especially recommend playing it with wizards in the party. If you somehow put together an all-wizard campaign set in the Realms, there’s a lot to be said for using this level by itself.


Level 10: Muiral’s Gauntlet

Character Level: 11th
Theme: Beginning of the drow arc
Tone: Tension from treachery

There’s a lot of room to tour drow culture here, including plenty of drow who are willing to talk. As with a lot of levels, there’s a fragile balance of power that the PCs disrupt, which makes for a lot of conversations before fighting. There’s also conflict with the forces of another level, so it’s easy to think one might move between 10, 11, and 12 repeatedly and develop a stronger sense of place.

Because of Muiral, this is more relevant to later levels.


Level 11: Troglodyte Warrens

Character Level: 11th
Theme: Battleground
Tone: Constant conflict

This is the second part of a major drow arc, but there are a lot of other things than drow here. Even here, there are a lot of fights with low-end creatures in medium to large groups. As I imagine running this, I think this is a point at which dungeon fatigue would be a considerable problem – ultimately you’re doing a lot of carving your way through ever greater numbers of creatures without a lot of change in your goals or stakes, unless they’re uncommonly invested in fighting one or both sides of the drow house war. If you start having a problem with this, encourage the party to withdraw to Waterdeep and play some different content for a while.


Level 12: Maze Level

Character Level: 12th
Theme: Conclusion of the drow arc
Tone: Besieged

Looking at the whole drow house war, it’s not immediately obvious that the characters would engage with it directly. Leaving the two Houses to their own devices does make things substantially worse, but the various portals probably mean you can avoid the problem or postpone worrying about it for a long time. That said, parties that decide to care about the outcome, even arbitrarily, will find an interesting and tense situation that can really come to life once a DM grants them agency. (Consider how Chris Perkins brings the starting situation of Barovia to life in DCA for an object lesson.)


Level 13: Triobriand’s Graveyard

Character Level: 12th
Theme: Constructs and magitech
Tone: Incomplete potential

I like what goes on here. There are opportunities to learn about Triobriand, leading to a later direct encounter. This is far from the last we’ll see of massive metal constructs, as well. It’s also great to see a level whose central figure (other than Triobriand) is benign. It should be a fairly brief level, overall – its map is the same size as any other, but it’s made up of a smaller number of very large chambers.


Level 14: Arcturiadoom

Character Level: 13th
Theme: Reconstruction and transformation
Tone: Gonzo

This is one of the first direct looks at Halaster’s longer-term plans. Some portions of this level are also very important for later encounters. We’re getting a lot deeper into the stories of Halaster’s apprentices now, so I don’t recommend skipping this level for any group that is serious about taking on the final level of the adventure.

Some of the things revealed on this level are gonzo, others simply weird. This level is the one that first made me decide to note theme and tone for every dungeon level, because this one is a sharp contrast. The problem is, after many levels where this wasn’t true, this level goes back to having several encounters where the right answer is total avoidance. There’s no reward other than experience points for engaging in the first place – and if you’re engaging with an encounter only so that you’ll get XP when you eventually stab it, I think that’s a fundamental failure on the writer’s side.


Level 15: Obstacle Course

Character Level: 13th
Theme: Don’t split the party!… you split the party.
Tone: Silly, possibly in a horrific way (a la Beetlejuice)

So about that tonal contrast. I’m pretty sure there’s no explanation for how Halaster came up with this that doesn’t involve magical contact with 20th or 21st-century Earth. It’s a long, long way from what I usually prefer in games I run or play.

At the same time, this is probably one of the most dangerous levels the PCs will have encountered so far. Any Elder Rune could be your abrupt demise, because Halaster is a jerkface, The level also works hard to split the party, so you might be taking on some fights alone. Even high-level characters could get very murdered in such a situation.

I think the best approach to running this level is to play it garish and gory, creating tension and fear by keeping the players on their back foot and steadily wearing them down. It probably ends – if the DM doesn’t actively prevent it – in at least one completely unfair death from something or other. It could definitely be a horrific experience.

It also plants the seeds of another multi-level arc, in this case the three-sided githyanki/githzerai/illithid fights.


Level 16: Crystal Labyrinth

Character Level: 14th
Theme: …In Spaaaace
Tone: Serious

This is one of the main areas of the aforementioned three-sided conflict. If the DM hasn’t given the PCs a reason to hate githyanki (which, in fairness, isn’t hard to do; githyanki are antiheroes or sympathetic villains on their good days), avoiding this level is a pretty rational character decision. Not many PCs are going to pick a fight with githyanki and their allies if they think there might be a bunch of illithids right around the corner, you know?

As it happens, I really like Stardock, githyanki, and Astral or spelljamming helms, so this whole level is great to me. Obviously, if there are githyanki or githzerai PCs in your party, this is even more of a must-play.


Level 17: Seadeeps

Character Level: 14th
Theme: Illithid psi-tech
Tone: One massive mindscrew, or quasi-Lovecraftian horror

This level has one of the coolest ideas in the whole book. I just have this fear that a bunch of parties are going to approach this level by carving their way through it and not getting much of the story, and that’s a crying shame – it is really, really cool. For the most part, this level also concludes the story of the githyanki vs. the illithids.

As far as I’m concerned, you should lay groundwork to run this level from 1st level in any Waterdeep campaign, regardless of whether or not it’s otherwise an Undermountain campaign.


Level 18: Vanrakdoom

Character Level: 15th
Theme: Grief and memory
Tone: Horror, maybe gothic

This level is here to tell a specific story, and one that would not be out of place in the Demiplane of Dread. I like what goes on here, including the planar interactions, though my favorite part of the whole thing is a reveal in the Aftermath. My criticism of the whole level is that you get the ideal weapon for most of the enemies here early on, and probably go through the rest of the level like a bandsaw through a duck. It is probably hard to take a long rest here without leaving Undermountain, but that’s a lot of fights to rely on slow attrition.


Level 19: Caverns of Ooze

Character Level: 15th
Theme: Slimy slime slime
Tone: Goofy comic relief

You could get some serious tonal whiplash going from level 18 to 19. “Whimsical even by Undermountain standards” is putting it mildly, I feel. My advice for running this is to be absolutely sure the party returns to Waterdeep and has some more involved interactions there between levels 18 and 19, as a palate cleanser. There’s another big Spelljammer setting piece here, plus a pretty on-the-nose reference to The Great Modron March. Make what you will of that.

One important thing is on this level as well, setting up the story of an opponent within Undermountain who actually vexes Halaster. If you decide to skip this level, just move that thing somewhere else.


Level 20: Runestone Caverns

Character Level: 16th
Theme: Decay
Tone: Tension from nearing the endgame

This level seems like it should pose a credible threat, even to high-level characters. Overall, I like what goes on here. There isn’t a ton more to say about it – it’s fundamentally a straightforward seek-and-destroy.

The first hints of level 22 show up here.


Level 21: Terminus Level

Character Level: 16th
Theme: Corruption and disguise
Tone: Grim

Fazrian’s story is definitely my kind of thing. My only complaint about it is that there are some skill check DCs that are flat-out unreachable for many characters, and unreliable even when it’s your specialty. I’m a fan of this level.


Level 22: Shadowdusk Hold

Character Level: 17th
Theme: Lovecraftian/gothic horror
Tone: Horror

My one criticism of this level is its placement in the flow of the adventure as a whole. If taken all by itself, it would be a substantial dungeon crawl. Placed here, it’s a big final roadblock to getting to the final level. I strongly recommend a trip back to the surface for a palate cleanse and advancing personal storylines before and after this level. Even though you’re getting close to the end, don’t be afraid to slow down and remind PCs of what they’re defending.

With that out of the way, it’s a great piece, invoking all of the best parts of Edgar Allan Poe and Lovecraft in its style. The story is self-contained enough that it’s a fine candidate for using independently of the rest of Undermountain, and it involves a plot against the city as a hook. What’s not to like?


Level 23: Mad Wizard’s Lair

Character Level: 17th
Theme: Endgame
Tone: Highly varied

The darkly comic, anachronistic style that has shown up several times in Halaster’s personal work is the central attraction here. Confrontation with Halaster isn’t a foregone conclusion, and I think that’s one of the most interesting things about the whole book. This level also offers conclusions to many of the side-plots about his apprentices.



I’m skimming this especially lightly, but I love that it’s here. Every time I’ve recommended that players withdraw to Waterdeep for an interlude, Skullport works just as well (but with a very different tone). The city can easily become its own setting for a story arc or short campaign – it’s Blades in the Dark waiting to happen. Skullport starts out more empty than full, so the more you want PCs to be here, the more you should probably give them ways to draw more people here and establish a power base separate from Xanathar.



I think there are a lot of those personal stories that the book explains, but doesn’t quite get around to showing DMs how to reveal to players. When running Dungeon of the Mad Mage, DMs need to seize every opportunity to have NPCs throw information at them. Encourage players to retreat to the surface and seek out answers to secrets in libraries there. Consider writing extra text handouts; letters sent back and forth between Halaster’s apprentices or illusory recordings of conferences between them could do a lot to make sure players understand those stories.

I said this at the top of the review and I’ll say it again: treat the whole book as a toolbox, not a straight-line route. There are a lot of strong, compelling personalities here, from Arcturia through Zox, so give them as many chances as possible to bounce off of the PCs and each other. This is a core tenet of good game-running that is too easy to forget in dungeon-running: emphasize responsiveness. The static nature of the words on the page and in media res style of many encounters can trick DMs into forgetting this.

Keep your eye on how you’re drawing the PCs onward and downward. It would be easy to stall out midway through, for various values of “midway.” There are a lot of distinct story arcs here. The introduction and exposition of new arcs isn’t always focused on emotionally hooking the players the way it needs to be. There are, again, only a tiny number of delineated quest hooks in the book.

All that said, I think this is a very strong text. The maps are great, the expansibility is great, the new stat blocks in the back of the book are great, the new magic items (presented in-line in the adventure, not in a separate section) are great. You can use individual levels to good effect, as though this were Tales from the Yawning Portal.

It offers tonal consistency within a level, but not level-by-level, so you can either cut levels entirely or look for alternate approaches if you want a particular tone for the whole campaign. There are plausible tweaks to bring the more comic or anachronistic levels into line with a tense or horrific tone.

High marks, all around. I don’t think it’ll be as popular with the actual play streamers as Waterdeep: Dragon Heist, but I hope I’m at least a little wrong there. In my view, this is the high bar among all presentations of Undermountain to date.