Waterdeep: Dragon Heist is an urban adventure for level 1-5 characters, as well as being a sourcebook for play in the City of Waterdeep. However, it’s not the only adventure release coming from Wizards this year!

The second adventure release is the linked product Waterdeep: Dungeon of the Mad Mage. This one’s for levels 5-20 and covers 23 levels of the great dungeon of Undermountain, which lies under the City of Waterdeep.

Those expecting the entire dungeon in one book are likely to be disappointed. Undermountain is too big for that. It’s had two boxed sets, a hardcover book and several shorter adventure releases in previous editions, and none of them has covered it in full. The original Undermountain boxed set? It came with four poster maps covering only three levels of the dungeon, and only detailed a small portion of those levels!

Dungeon of the Mad Mage will instead give partial maps of each level. Those partial levels should be well-detailed. Corridors will lead off the map, and the areas they lead to will be left up to individual DMs to describe.

What’s particularly interesting about this adventure is how much of the dungeon it describes. Twenty-three levels. Yes, a portion only thereof, but that’s more levels than we’ve ever had before. Each level has a different them. A lot of people contributed to the adventure, including all the D&D Adventurers League administrators, so the diversity of approaches is likely to provide a similarly diverse adventuring experience.

I first used Undermountain in 1992 when a band of adventurers were accidentally teleported into its depths. They didn’t spend long there, but it led to one of my enduring highlights of the D&D game. We were using a precursor to the Perception rules, and the party rolled a critical failure to determine what was in the next room. Instead of describing the pair of skeletons that was there, I told them there were “329 skeletons”, and was much amused as they fled in haste, the “horde” in pursuit. Only when they fled into a dead-end and discovered only two skeletons were pursuing them did I reveal the error!

Undermountain is one of the rare megadungeons that has been published – even if only partially. What’s a megadungeon? It’s an enormous dungeon! My definition of one is a dungeon that’s big enough to support multiple adventuring parties in it at the same time. In the early days of D&D, that was the type of play that often occurred. A DM would create a dungeon, and then all their friends would adventure through it, but often in separate adventuring parties. You can find these types of dungeons described in early D&D fanzines and the like, and certain sections of the AD&D rules don’t make sense without knowing that.

Most megadungeons don’t get published, because they’re too big. Running such a dungeon is a different experience to the one-shot dungeons we normally run. These are dungeons that get revisited. As a result, you often restock rooms, replacing the original inhabitants (now fled or dead) with new ones, and keeping the environment fresh for the adventurers. Not every inhabitant is a foe. Feuding factions exist, allowing the adventurers to ally with one side, or to play one off against another. Dynamic dungeons are hard to write well. In addition, the DMs who designed them – like Gary Gygax – would have very brief notes as to what was in each room; nothing near publishing quality. And each copy wasn’t shipped with a clone of Gary Gygax to interpret the maps.

(Indeed, we never did get Gary’s version of Castle Greyhawk.)

Play of Dungeon of the Mad Mage is likely to be more straightforward in the D&D Adventurers League. It’s difficult to restock rooms in Organised Play and maintain balance between various groups. (So, you’re saying that this rooms contains five kobolds wielding a staff of power?) There may be rules for doing so, but I’m not holding my breath expecting them. Instead, the DDAL play is going to be “Here’s a big dungeon. Explore it!”, though the factions and strange levels and interesting tricks will still be there. Given that the DDAL admin team had a big hand in designing this dungeon, at least they know the limitations on DDAL play – with luck, the design will reflect them!

For non-DDAL play, the Dungeon of the Mad Mage is going to be a starting point. Here’s inspiration. Here’s a lot of detailed dungeon areas. What else can you create?

Oh, and there’ll be a description of Skullport as well.

Dungeon of the Mad Mage has a November release date; a few months after Dragon Heist in September.