The role of Dungeon Master, or DM, is a challenging yet rewarding one in Dungeons & Dragons. The DM is the one who runs the entire game world in any campaign or one-shot, such as describing the setting, voicing the NPCs, controlling the monsters, and making judgment calls about how certain things work. Being a proper DM calls for all kinds of prep work for each session in a D&D group, and novice DMs are encouraged to learn some basic points before they run a session.

While the players are expected to control their own characters and perhaps keep notes on the campaign's progress thus far, the DM must juggle a lot more material behind the DM screen, from monster models to developing the story to inventing homebrew material and making sure the pacing stays on track. If the DM can handle three basic topics in particular, the rest should prove easy. Those topics are game supplies, pacing the story, and running the story without being too rigid or getting lost in the process.

The Dungeon Master Must Plan For the Right Game Supplies and Physical Environment

• The typical Dungeons & Dragons session lasts between 3–5 hours.

Unlike video games, Dungeons & Dragons calls for a variety of physical components that must all be used just right to make the game work. At least, this prep rule applies to the traditional way of playing the game on a tabletop and everyone seated together. Playing online is a different matter, such as using digital maps and character tokens, along with having video and audio for all players. That kind of prep calls for computer know-how, while preparing for a traditional D&D session requires more work — and can be even more rewarding.

If a D&D group only recently game together or was forced to change venues since the last session, then the DM — perhaps with the aid of some players — must find the right environment in which to play this game. One common example is the DM's own residence, such as their kitchen or living room, complete with a table and chairs, or perhaps a player's residence. Or, the DM can find a local game store/LGS and ask if they have room for D&D sessions. Many game stores are ready to accommodate player groups who spend hours with games like D&D and Warhammer 40,000, so this may be relatively easy. Still, the DM must double-check and be sure their LGS can accommodate their group. This also involves checking the game store's business hours and any game room fees that there might be.

If the venue is already settled, then for each session, the DM is expected to have all the right props and gaming supplies on hand to run the session. There are many D&D supplies to consider, including the DM's own dice, typically used to roll for monsters' actions in battle, such as attack rolls and the damage of spells. That also calls for having a dice tray in which dice may be rolled without getting lost. The DM must also have their DM screen, which serves two purposes — hiding what the DM is doing, and providing reference with info sheets on the inside. All these things are used for every session, so those are factors to consider when the DM is launching a group's first session.

For regular sessions, the DM is encouraged to assemble any monster figurines, terrain, maps, and perhaps NPC figurines. For budget or practical reasons, or just for personal preference, the DM might do away with these things and use theater of the mind instead, but if props are used, then the DM should refer to the session's intended adventures and gather everything that is needed. If the party will fight a squad of bandits backed up by a blue slaad, for example, those monster models and their stat blocks (physical or digital) should be ready, hidden behind the DM screen. The same is true for terrain such as trees, rocks, buildings, wells, and statues. The DM should also have any necessary maps prepared, some of which might have specific terrain on them. If the party will fight near a creek with a bridge, they must get the right map, to name one example.

The Dungeon Master Must Prepare the Session's Adventures While Leaving Room For Improv

• The ideal D&D party size is 3-5 players, although experienced DMs often accommodate more.

Whether a DM is running a one-shot or a campaign, or whether they play online or in person, they absolutely must have the day's adventure ready. If the session involves a homebrew adventure, then the DM will think up the setting, monster, quest, and all other story material, which will take some effort but may be highly rewarding. If the DM is running a pre-existing adventure, such as The Lost Mine of Phandelver or Curse of Strahd, then the DM should read the correct part of the book and get a firm grasp of the material.

The DM isn't expected to memorize it word for word, but they should definitely learn the basic points of the adventure to see what the party should do and how the story can move forward as intended. This includes knowing the layouts of dungeons, knowing where certain NPCs can be met, where the traps are, where magic items may be found, and so on.

The trickiest part of preparing the session is striking the right balance between having the player party follow the quest and allowing them to make up their own quest as they go. This will get easier with practice. If a DM tries to force the party to follow an adventure like Vecna: Eve of Ruin exactly as written, they risk railroading the party and robbing the players of their agency. Conversely, if the DM allows the adventure to wander too far off the intended path, it may be tough to get things back on track, and the campaign might stall out.

So, the DM is encouraged to prepare for each session by knowing the core of that day's adventure while also leaving ample room for players' improvisation during gameplay. The DM will know which story beats must happen while also knowing how to fill in the gaps when the party goes off-script en route to the biggest plot points.

This can take a variety of forms. For example, the DM can take note of the session's locations and prepare to roleplay not just the major locations, such as the villains' castle or the local tavern, but also "off the beaten path" locations that the party may visit. An adventure may not expect the party to break into the gardener's locked shed and look around, but if the party's wily rogue does just that, then the DM should be ready to narrate something interesting.

The idea is that there should always be some kind of payoff for a player's actions, whether it's finding a magical item, meeting an NPC, or even stumbling into a scary trap. The payoff doesn't have to be positive, but it must be something that demands the player's attention, so they feel like their actions mean something. A DM is encouraged to fill in the seemingly unimportant corners of a game setting beforehand to make sure there's always something fun to do.

The Dungeon Master Should Figure Out How This Session Connects to the Others

• DMs and players alike can find plenty of supplemental material and resources online, either from official channels or fan sites.
• Popular sites include D&D Beyond, D&D Compendium, and Dwarven Forge.

No Dungeons & Dragons session exists purely in a vacuum, not even a one-shot. It's true that by nature, one-shot adventures are largely self-contained and aren't worked into a larger campaign, but even so, the DM is advised to prepare some context for that one-shot. The DM can think up some context for how a one-time crew of characters met up and where they are, along with why they are a team undertaking this adventure together.

One-shots may be self-contained, but players may still expect the adventure to be somewhat grounded and provide a "why" for the entire adventure. Fortunately, some anthology books such as Candlekeep Mysteries and Journeys Through the Radiant Citadel provide settings like the Candlekeep mega-library to help contextualize things. Many of the adventures found inside will do the same, complete with plot hooks. And there's room for the DM to add more plot hooks if they so choose.

As for a campaign with a chain of sessions, it's even more important for the DM to keep the pacing even and make sure each session begins and ends strongly. Each session is like a chapter in a book or an episode in a TV show, and the pacing will be stronger if each session starts with something fun to do and ends with a mission well done or a dire new threat to face next time. Before launching another session for their campaign, the DM should review what happened next time and include things like an NPC ally or a monster that's pursuing the party, or keep track of an ongoing situation, such as a race against time.

The DM should also figure out a few places where the session should end. Multiple ending points should be chosen because there's no telling how long the party will take to arrive at any of them, and their actions may lead them toward certain ending points and away from others. The DM could always use the clock to decide when to end a session, but a weak or abrupt ending may disappoint some players. Ideally, to reinforce the story theme of a D&D session, the DM will prepare to end a session the way they would a book chapter or TV show episode, such as with a dramatic reveal, a cliffhanger, or a much-needed long rest between battles or conflicts. That will give the players a sense of accomplishment while also getting them excited for what is to come.