A DM’s Guide to Undermountain: A Very First Look

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A DM’s Guide to Undermountain: A Very First Look

There won’t be a lot of articles about Dungeon of the Mad Mage for a while, because that’s the campaign I’m currently running, and I really do like to wait until I have something authoritatively based on actual experience to say before I open up my keyboard and start spewing pixels. However, this article is here because I can make some observations and suggestions on how to run Undermountain in a general way, based on my experience running other large dungeons with similar features. Eventually, I’ll have built up a trove of hard-won insights and war stories for the various levels of the dungeon, and then you’ll start to see more regular articles coming out. For now, I’ll just give my best advice for Dungeon Masters who are just starting out on Undermountain… like me.

Undermountain Is Massive

The first thing to get out of the way is that Undermountain is a really, really big dungeon complex, and there are a lot of different things in it, and very large dungeons take a lot of planning and prep work if they’re going to run smoothly. Please bear in mind that I run my games old-school, which means that I use lots and lots of paper and mechanical pencil lead refills. My rulebooks are all actual books, as are any other books that I need to use. Monster stat blocks are written out on index cards. Spells are either on spell cards or marked in the PHB somehow. All of my notes are either scribbled in a notebook, or maybe typed up in MS Word and then printed out.

You Heard That Right. No Electronics for Me.

Yes, I know about D&D Beyond. I really like D&D Beyond, because it does help me not have to get out of my easy chair and find my reference books when I just need to look up a spell or two. But I don’t use D&D Beyond to run my games, at all. Not even to look up a quick spell or monster. If you like to use electronics to run your games, that’s obviously your choice, and I’m not the kind of fascist purist who thinks that my way of doing things is the only right and true way of being a DM. Nevertheless, it is my way of doing things, so a lot of the advice you’re going to get in this article is based on using lots of paper and no pixels. Take it or leave it, according to your own preferences by which you run your own games. If you want DM advice about how to run Undermountain using D&D Beyond, or Roll20, or Fantasy Grounds, you’re not going to find it here. Not because it’s bad, but because I don’t know anything about running a game with that stuff. Enough said.

Making and Using a Card File

Just to say it up front, if you’re not planning on using a boatload of index cards to run Undermountain, you can skip over this section. Unless, of course, you find it interesting and educational to read over ideas that you don’t plan on using, because maybe you’ll need to use something like that one day. Some people are like that. So read on, or skip ahead to Dungeon Level Preparations.

So, if you like to keep all of your monster and NPC stats on some kind of paper, like I do, using index cards is a pretty good way to go. Aside from some of the really legendary or heavy spell-casting enemies, a 4-by-6 index card will hold everything you need to know from a Monster Manual stat block. I also write down the Monster Manual page number on that index card, just in case I need to look at the source for some reason. My shorthand entries for certain effects often seem really clear when I write them and then less so during the actual game, so having that page number makes looking up the monster as quick as possible.

For some of the enemies that do have a lot more information in their stat blocks than the usual run-of-the-mill monsters, I just write down the name of the monster and the Monster Manual page number on the card. There’s nothing wrong with going to the Monster Manual to look up a stat block, but you don’t want to do it too often, or it will drag down the pace of your game. But, you’re not going to get the beholder stat block, or the ancient dragon stat block, or even the vampire stat block on a single card, even if you try to put things on the back of the card (which is very inconvenient, by the way, and should be avoided). Just plan on turning to the right Monster Manual page for those. It’s the best strategy.

Card File Pitfalls

For some adventures, you can build a fairly simple card file by area number, or by chapter, or by dungeon level, or some combination of those. But, when you run into really huge dungeons like Undermountain, things get hairy. For one thing, areas on each dungeon level tend to re-use a lot of monsters, so splitting the card file into dungeon level subdivided by area number doesn’t work so well: you end up needing multiple copies of certain stat blocks in order to put one “goblin” card in every numbered area that has goblins in it. That’s a bad way to do it.

If you’re going to build a workable card file for Undermountain, you’re going to have to split it up by dungeon level only, so all of the cards you need for a certain dungeon level are grouped together, and you have to find the ones you need as quickly as you can. Starting out with them alphabetized helps, but I guarantee they won’t stay that way long when the game starts moving along. Get ready to add re-alphabetizing index cards to your game preparation tasks.

But, there’s another problem with building your card file by dungeon level, and it’s the same problem that you would have if you built your file by area number. It’s just one organizational step higher. You see, a lot of monsters appear in multiple dungeon levels, and you really don’t want to have to create a copy of the same stat block on separate index cards for each dungeon level that contains a certain monster. There are twenty-three levels of Undermountain, and that means you might have to create a dozen identical cards for a certain type of monster that is commonly found on many different levels. That’s also a bad way to do it, and I’ll tell you the reasons why.

There are actually two main reasons why that’s a bad way to do it. One is duplication of effort. Why would you want to spend time and effort to make a lot of identical “goblin” cards when you could make it work with just one of them? The other reason is that cards take up physical space. Individually, they don’t take up a lot of space, but it adds up. I’m going to tell you about the most efficient way I can think of to make a comprehensive card file for all of Undermountain, and it’s still going to take you three or four hundred cards. And that’s the efficient way to do it. If that sends you running for D&D Beyond, I don’t fault you for an instant. I wouldn’t have faulted you before, either, but sometimes using only paper and pencil for a paper-and-pencil RPG is not for the faint of heart.

Building Your Card File the Smart Way

If you want to get your Undermountain card file down to a number of cards that will fit in a single one of those plastic card file holding boxes, here’s how you’ll need to work it. You need to have a section for each of the 23 levels of the dungeon, as well as a section we’ll call “Commons”, a section called “Standards”, and a section called “Specials”. At least, that’s what I call my sections. Once you figure out what they’re for, name them anything you want.

We’ll work backwards. “Specials” will contain stat blocks for important NPC’s or unique monsters, and the distinguishing feature of all of the cards in this section will be that they are based on a general stat block, but with specific and significant changes. If you have an NPC named Trevor who uses a “thug” stat block, but with a different AC, and some other weapons and attacks, and damage resistances, then make a “Trevor” card with all of those changes on it and put it in Specials. That’s what Specials is there for. Mark on the Trevor card the page number for the basic stat block, and also the page number where all of the changes that make Trevor so different can be found. Remember, in order for a card to go into Specials, we’re talking about a lot of changes to the standard stat block. If the changes are few or minor, you’re going to use a card from “Standards” instead.

“Standards” is going to be the section that has all of the standard NPC stat blocks from Appendix B in the Monster Manual. All of your acolytes, assassins, and archmages will go in here. In a general way, your adventure module or hardcover book will probably also have some additional NPC stat blocks, so those need to be included too. Make a card for each of them. There are going to be a lot of NPC’s throughout the campaign who fit one of those named stat blocks almost exactly, with maybe a few minor changes to languages, racial traits, or prepared spells. You don’t need a card in Specials for those NPC’s. Just have the basic stat block in Standards, and make the small changes when you play the NPC, based on the information about the NPC that will be given in the appropriate part of the hardcover book.

“Commons” will be a huge section. You will have to organize it alphabetically. No two ways about that. I suggest that you get extra dividers so that you can split the alphabet up in to “A through D”, “E through J”, and so forth. I actually even included some subdivisions for monster categories like fiends and beasts. We talked about using hundreds of cards in this file, and maybe half of those will be Commons. And that’s because Commons will contain every stat block that appears in at least two different dungeon levels. When you get ready to run a dungeon level, you’re going to go into the Commons section and pull out all of the stat block cards you need for that particular level, and when you’re done with that dungeon level, you’re going to put them all back so they’ll be there when you need them for another dungeon level. Commons is how we keep from duplicating effort, and from taking up more space than is absolutely necessary. Commons is what makes it possible for our card file to contain exactly one stat block card for each monster or NPC in the entire dungeon.

And, finally, there will be a section for each of the twenty-three dungeon levels. That section will contain all of the stat block cards for monsters that show up only on that particular dungeon level and nowhere else. And, right at the front, there will be a card that reads “Level X: Pull From Commons” at the top, and then gives an alphabetical listing of all of the stat block cards that will need to come out of the Commons section when you start running that dungeon level, and then go back into the Commons section when you’re done with the level.

If you do it this way, you can fit the entire Undermountain card file into just one of those plastic card-file boxes. It’ll be a tight fit, but it will fit. I’m not going to tell you how to figure out what belongs in Commons and what doesn’t, though, because I honestly don’t know how you’re personally going to make it work. I had a particular personal advantage when I did mine, and that might make your process different.

I’m told there’s no such thing as photographic memories, or even maybe those eidetic memories you hear about sometimes, but I have a memory that works about as closely to that as can be expected. When I made up my card file, and I came across a stat block that I needed for Level 17, and it also happened that I had made up a card for that stat block already back in Level 5, I would remember that I had done that card already and where I had put it. Then I would go back to the Level 5 section, move the card to Commons, annotate that on the Level 5 Pulls card and the Level 17 Pulls card, and continue on. If your memory doesn’t work that way, you’ll have to come up with some other way to do it.

The best way that I can think of that doesn’t require that kind of memory would be to create a list of all of the stat blocks you need by level, before you start actually creating the stat block cards with all of the information on them, so just a list of monster names for all of the monsters found in each dungeon level. If you do it that way, you should be able to look through your separate level lists and identify monsters that appear more than once, even though it might take a few passes through the stack to get them all. Then you would start actually making the cards with the stats on them.

Anyway, that’s a problem you’re going to have to solve for yourself if you want to use my model for building your card file, and I think at this point I’ve been as helpful as I can be on the issue. But, once you figure out how to get everything into Commons that belongs there, you’ll have all of your card file sections ready to go.

And yes, you may be deciding right now that you’re going with D&D Beyond from here on in. I completely understand. After all, making the card file as described took me about three days to get it all done, working pretty steadily but with lots of breaks to stop my writing hand from cramping up permanently. Also, you’re going to have to do the entire card file before you run any of the adventure. The way the system works doesn’t readily lend itself to gradual expansion. It’s not the best method for everyone, but now you know how to do it.

Dungeon Level Preparations

Whether you go with cards, or pixels, or whatever other method of handling monster and NPC stats in a smooth and sane fashion, there will be some preparations that will need to be made for each dungeon level before you can run it. We’ll go through those next, starting with the all-important topic of cartography.

Dealing with Maps

If you’ve run Dragon Heist, or at least seen the inside of the book, you’ve already seen the style of the Undermountain maps. They are black and white line-drawing maps, not the full-color glossy with tiny realistic details maps like you’ve seen in previous hardcovers. The best way to make the distinction is that the maps of Undermountain are like Google Maps that just show the streets and their names, and the maps from hardcovers like Tomb of Annihilation are like the Google Maps satellite look-down mode. I kind of like the stark, black-and-white map style, because it’s a lot easier to make notes on than the colorful maps.

And make notes you shall, because without that little satellite look-down it’s very easy to forget what’s in any particular room, and you need to be able to tell at a glance what goes where on your map. Looking up the area number is not going to be quick enough for your players to explore smoothly. I’m using three colors of ink to annotate my maps: green for a general two-or-three-word room description, blue for NPC’s or special features, and red to alert me to traps or monsters. You could get away with just giving brief room descriptions and some sort of mark to make sure your traps don’t get forgotten, but that would be a minimum. Make photocopies of the maps for each level, because then you won’t have to flip back and forth in the book between the map page and the room description page you’re currently using.

A Segue Into Halaster’s Gates

If you’ve read through the introductory material for Dungeon of the Mad Mage, you know that there are magical gates that lead between levels of the dungeon. Think of them as express elevators with stops at only two floors. The intro talks about how to use the gates, and when you can’t, and how Jhesiyra Kestellharp will stop characters from using gates that are too high a level for them.

DM’s who are using the pencil-and-paper-purist methods I’ve been discussing will need to place an additional restriction on gates. The restriction is that you can only use a gate to travel to a level of the dungeon where you have already been. So, taking the gate from Level 10 back to Level 1 is no problem. Taking the gate from Level 1 to Level 10 is only allowed if you’ve already been down to Level 10. There’s a very good reason for this, and the reason is preparation.

Quite aside from the card file, and the annotated maps, there are a lot of important things to know about and to be ready to manage for each dungeon level. There are NPC’s, and factions, and motivations, and conflicts. You may even add more of that sort of thing to some of the levels to make them more interesting. This is not just a dungeon crawl through deeper levels with meaner monsters, folks. This is a living, breathing dungeon complex, where the things your party does will make a difference to how things turn out, in the near term and in the long term. And that means that, unless you’re planning on the purely murder-hobo playstyle all the way through, you need to be able to prepare for each dungeon level in advance.

If the characters can use gates to run the dungeon levels in non-consecutive order, you as the DM will have to be prepared for them to travel to any level at any time, and that’s just too much to deal with. Give yourself a break, and just make them go down one level at a time, using the stairs. You’ll give yourself plenty of time to get ready for the upcoming dungeon levels that way, because you only need to stay a level or two ahead of the party.. Being a DM is hard enough, so don’t make it harder on yourself when you don’t absolutely need to. Just house-rule it and be done with the issue.

More About Those Gates

This is not something I’m happy about having to tell you, but you really need to have a map of all the gates: what level and area they start in, what level and area they end in, and maybe what the required level to use the gate will be. Here is a picture of the one that I made. I hope that you can read it well enough to use it yourself. If you can’t, well, at least you can see how I set it up: levels in descending order in the left margin, area numbers for the levels on the appropriate horizontal lines, a vertical line connecting the area numbers for each gate, and the level requirement written along that vertical line. This image is probably one of the most useful things that will ever be posted on this site, no holds barred, and that’s saying something.

This is a watermarked image of a chart made to illustrate Halaster's magic gates for Dungeon of the Mad Mage.

You can see the first gate goes from Level 1 , Area 26D, down to Level 10, Area 8. The number written along the vertical line tells us that this gate is intended for character levels 11 and up.

The hard truth is that you’re probably going to be the one who keeps track of the gates and where they are and where they go, because your players aren’t going to have the overall visibility required to look at that chart and know what it all means. I don’t even plan on telling my players how far down the dungeon goes, actually. When they get to the bottom, it’ll be a surprise. So, when the players need to get back up to the surface, you’ll probably be the one telling them which gates to use and how to get to them. Give them some options, if there’s more than one set of gates to use, or if there’s more than one way to get from one gate location to the next on a particular level, but unless you plan on giving your players copies of all of the maps and the gates chart (I suggest that you don’t do that) you’re going to have to manage the gates for them.

Undermountain: More than a Hoagie

Undermountain isn’t just a giant sandwich of monsters and rocks. The levels of the dungeon are interconnected, with interactions that make a difference for the dungeon as a whole, and which are to a significant extent dependent on the choices and actions of the PC’s. You’re going to have to treat it as such, unless you really just do want a monster-and-rock sandwich. Some groups want that sort of thing, and don’t care about far-reaching consequences, NPC ambitions, and overall story progression. I think most groups are going to need at least some of those things if they’re going to maintain interest in Undermountain, especially after Ghosts of Saltmarsh comes out (which is in just about a month as of the time I’m writing this article).

Ups and Downs

Remember, there are things that are happening on the various levels, and the actions that the PC’s take on those levels will have lasting effects on the future states of those levels. Fact is, they will be passing through Level 1 every single time that they come back up to the surface to rest, resupply, or whatever. Whenever the party changes something in Level 1, I plan to have consequences of those changes ready to show them the next time they pass through. Bear that in mind: there are not very many one-night-stands in this dungeon. Most locations will be passed through more than once, so be ready to show some changes and consequences on the party’s next time through.

Halaster’s Non-Compelling Goals

This is a place where I think the hardcover has let us down. If you look at the sidebar on page 11, the book provides six possible goals for Halaster, which are supposed to be the reasons why he tolerates adventuring parties in his home, and how he’s attempting to use or manipulate the party into furthering his own aims. The sidebar even suggests rolling a d6 to decide what goal to use, which is a ridiculous notion. Also, three of the six goals are utterly pointless, two of the remaining goals are so specific as to have little or no effect on most of the dungeon, and the final goal is just kind of boring and geared towards the murder-hobo adventuring style. So, let’s go over why the goals in the book don’t work, and then I’ll suggest something better.

Goal 1: Clean House. This is the murder-hobo goal. Essentially, for this goal Halaster wants the PC’s (or anybody, really) to clear the drow out of Levels 3, 10, and 12. He’d also like to see the githyanki and the mind flayers cleared out of Levels 16 and 17. So essentially this is a go-in-and-kill-everything type of goal. It also only affects 5 out of 23 dungeon levels.

Goal 2: Destroy Ezzat. This goal only involves Level 20, where Ezzat can be found, and Level 19, where some allies who will help destroy Ezzat can be found. So that’s 2 out of 23 levels affected.

Goal 3: Strike Fear into Heroes’ Hearts. This is one of the utterly pointless goals. People are already afraid of Undermountain. People already tell stories about the horrors within. Essentially, this goal has already been completed, and it’s going to continue to be completed without any further action on Halaster’s part.

Goal 4: Become Waterdeep’s Shadow Lord. This specifically says that it has to do only with the Shadowdusk family, who are on Level 22. And that’s the only place where this goal has any effect. That’s 1 out of 23 levels affected.

Goal 5: Find an Apprentice. This goal has potential, but it really only affects arcane spellcasters, who would be potential apprentices. Maybe Halaster spends time and effort trying to seduce them into his service as they move through the dungeon. And the rest of the non-arcane-spellcasters just go along for the ride.

Goal 6: Locate Jhesirya. If you read about Jhesirya on page 10, you know that she’s a bodiless spirit pervading the entire dungeon. You also know that the PC’s have no way to communicate directly with her. Somehow she’s supposed to be using the PC’s to overthrow Halaster, but the only ways we ever see her do that is by stopping or dissuading them from going to dungeon levels that they can’t handle. As far as a goal for Halaster to pursue, finding her is both almost impossible and also can’t be helped or hindered by the characters’ actions.

Giving Halaster Some Good Goals

Let’s get one thing out of the way quickly, before we even get into this section. Exploring and conquering Undermountain will take a lot of play time. This is a large-scale campaign, and large-scale campaigns need to have some kind of unifying element. Not every adventure in the campaign has to have a connection to the unifying element, but several of them should. It creates a sense of wholeness, and it creates a motivation for the players to soldier on, especially when you’re going to be taking months and months getting through it all. So, when we choose a goal for Halaster, it needs to be a complex goal that will make itself known on many (but not all) of the dungeon levels of Undermountain.

Using that sidebar as a starting point, the only goal that has the potential to span the entire campaign is Goal 4. If Halaster wants to seize control of Waterdeep, that creates the potential for heroic actions to prevent him from doing so, and heroic actions are what D&D heroes like to do. The problem with Goal 4 is that it’s foolishly limited. Sure, using the Shadowdusk family to try to get control of the city is a workable plan, but would an evil genius with a 23-level dungeon full of nasties, uglies, and assorted minions available hang all his hopes on a single strategy? Of course not, and that’s why we need to find other evil plan options for him in other parts of the dungeon.

Not all of the dungeon levels need to have anything to do with Halaster’s plans for the Waterdeep takeover, nor should they. But it makes sense for Halaster to have several evil plans in motion, and that provides opportunities for the PC’s to thwart several evil plans as they move deeper into the dungeon. I’ll give you a sampling of the evil plans I’ve come up with, and you’ll notice that some of them are just adaptations of the sidebar goals; the sidebar says choose just one, but go ahead and ignore that. You can use some or all of the samples below, or come up with your own, or decide that all of this is a crock and just go with something from the sidebar. It’s your game, after all, but here are some of my ideas for my game:

Halaster’s Evil Plans: Samples

On Level 4, Halaster would like to remove the aboleth Illuun from contention. Illuun’s plans to take over Undermountain for itself pose at least an inconvenience to Halaster’s other plans, and any blockade of Level 4 would impede plans to invade the city from below. This is an interesting choice for the PC’s, because Illunn is an evil and oppressive force, but also a source of opposition to Halaster. Which side do they take?

On Level 14, Halaster wants the fire giants to complete work on the Halaster construct, which will later be used to fight the Walking Statues during any potential Waterdeep takeover.

On Level 20, Halaster wants to eliminate the lich Ezzat, who is a stumbling block on the Mad Mage’s doorstep, and might foul up any or all of Halaster’s various plots. You can even choose a particular plot that Ezzat has in his sights. Foiling this evil plan will be interesting, because Ezzat is a really evil NPC as well. Do the PC’s take his side against Halaster, or work out some other option?

On Level 22, the Shadowdusk family are gathering strength in their stronghold under Halaster’s protection, and preparing to be used as a conduit into Waterdavian nobility. Halaster wants to use them to replace the city’s leaders, openly or covertly. He’d especially like to find out the identities of the Masked Lords of Waterdeep and secretly replace them all with Shadowdusks. Because nobody is supposed to know who the Masked Lords are, maybe nobody will even notice the change…

And those will be at least some of the evil plans Halaster has in the works to harm Waterdeep. I have several more, but I’m actually a little paranoid about putting the best ones up here in case they somehow get around to my players; the internet is funny that way. At least you have a few samples, so take a look at what’s going on in any dungeon level and decide if there’s an evil plot hook there.

Evil plots shouldn’t crop up on every level of the dungeon, but they need to show up often enough to create a sense of progress towards an ultimate goal for the players. If they keep foiling plots and going deeper into the dungeon, eventually there will be a showdown with Halaster himself, and most parties will be spoiling for that fight. If they win, they will have secured peace and safety for Waterdeep, at least for a while. If they lose, at least they’ve fouled up many of the Mad Mage’s plans, and they can go out in a blaze of 20th-level glory.

I’m even planning on using the under-used Jhesirya Kestellharp as a way to feed the players some information about the evil plots. Not a lot, but enough to help them figure out that something more sinister than usual is happening on certain dungeon levels, and then to provide some assistance to discover the plan and foil it. Let’s face it, if she really wants to harm Halaster, just stopping adventurers from wandering into dangerous areas is not a very effective tactic. She’s going to have to provide information, guidance, or sheer outright manipulation if she wants adventurers to even hamper Halaster’s plans, much less thwart them.

Remember, Jhesirya doesn’t necessarily care about the PC’s. She cares about damaging Halaster, and the PC’s are tools to that end. Some artisans care about their tools, and some just get new ones when the old ones wear out. You’ll have to decide for yourself what kind of personality Jhesirya will have, if you use her at all. But leaving her as a wishy-washy bodiless force seems like a waste of a potential ally to me.

Summing It All Up

For all of you Dungeon Masters that like to use lots of pencils and lots and lots of paper, hopefully you understand how I created my card file of stat blocks, and can make that system work for you as well. Or, perhaps after reading that section of the article you have decided that you’re going to become a D&D Beyond DM from now on. At least you were fairly warned, right?

Remember to prepare your maps beforehand. I prefer the more minimalist tone of the maps in Dungeon of the Mad Mage, but not having the little visual cues as to what’s in each room makes it hard to remember how things fit together. Make your photocopies, and then mark all over them.

Halaster’s magical gates will be a thorn in your side unless you’re really prepared to deal with them. And you’ll pretty much have to deal with them, because Undermountain isn’t designed to be run all the way through without ever coming up for air, and using the gates is the only way the party is going to get to the surface with any kind of timeliness. Plan to be the only person at the table who really understands those gates, because you probably will have to be.

I strongly advise you to look through the dungeon levels, see what’s there, and find some ways to use that stuff to make some evil plots for Halaster. Do this on more than one dungeon level, too, because evil geniuses don’t put all of their eggs in one basket, and then leave that basket lying around for heroes to find and kick over. Foiling these evil plots every few levels is going to create a thread of continuity for your players, and that’s going to build the level of engagement that you’ll need if you plan to spend months of game sessions on this dungeon. Don’t just pick a goal for Halaster from the sidebar, because you can do so much better than any of those. Trust me, there’s untapped potential in those dungeon levels, and all you have to do is think like a crazy villain for a little while.

And that’s where I’ll leave my commentary on Undermountain for now. When I’ve had a chance to run some of the adventure, I’ll be able to speak with a better measure of experience about how it can be done well, and you can look forward to more articles then. For now, you know how I’m applying my previous experience in order to prepare to run the adventure. I hope that using that experience works out well for me, and I hope that it’s helpful for you as well. Getting off to a good start isn’t always critical for a successful campaign, but it certainly doesn’t hurt. Until the next time I have something useful to say about Undermountain, I’ll just wish you all the very best of luck with it. Combine that luck with some guile, audacity, and improvisation, and you’ll do just fine.

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