Traditionally, the best way to learn how to DM is to play in a few games run by a veteran Dungeon Master. In many ways, the fine art of Dungeoncraft is a grand oral tradition passed from DM to DM that stretches all the way back to Gary Gygax and Dave Arneson. If it works, the following advice will help you get up and running even if you don't have access to a veteran.

Action and Reaction
The AD&D® game is one of action and reaction. As the DM, you begin the session by describing a scene or situation. The players react by describing the actions they wish to take. You react to their descriptions by deciding and announcing the outcomes of those actions. The players then react to the outcomes with new actions, and you react with still more outcomes. This process continues through the session and the entire campaign. The best way to illustrate is through the simple example in the box below:

Even this simple example reveals that the lion's share of DMing boils down to a trio of basic skills:

Providing effective descriptions.
Determining how to resolve the outcomes of the characters' actions.
Deciding when you should automatically reveal information and when you should force the players to specifically ask for information.
Providing Effective Descriptions
The first skill, providing effective descriptions, is by far the easiest to master. You've probably practiced it all your life. Giving accurate and interesting descriptions is an important part of the DM's job for a number of reasons, most of them obvious. If you can't effectively describe the rooms the heroes explore or the characters they meet, you'll only confuse the players and make it difficult for them to formulate actions in response to your situations. Neglecting to mention that open window on the north wall when the players are trapped in a burning inn, for example, might ruin your entire game. Similarly, droning on and on with boring descriptions of scenery is likely to put your players to sleep before the action even starts.

Although advice on improving your ability to provide descriptions is really the province of an English class, here are a few quick tips before moving on. First, if you're not completely comfortable inventing your own descriptions, stick with published adventures like those found in DUNGEON® Adventures. These offerings almost always include notes that help you describe the action and sometimes go so far as to provide complete, "ready to read" descriptions (usually boxed and shaded text). Although you'll still bear the brunt of the work, you're sure to find a good starting point incredibly helpful. After you get a couple of sessions under your belt, you'll almost certainly find yourself growing more and more comfortable with the notion of improvising your own descriptions. A simple tactic you can glean from the best published adventures is the idea of incorporating all of the heroes' senses into the descriptions that you create. Don't just tell the players what they see in the dungeon; tell them what they hear and even what they smell when appropriate. Done effectively, this will take some of the pressure off your shoulders by making your environment seem more real, allowing the players' own imaginations to fill any gaps or accidental omissions.

Also, never allow yourself to feel rushed while conducting a game session. If you're not sure what should happen next or how best to describe it, don't be afraid to pause for a few moments to think before you start talking. Your players certainly won't hold it against you, and, under most circumstances, the brief pause only adds another layer of suspense to the proceedings. Some beginning DMs tend to get nervous or "freeze up." Just remember, this is only a game. Nobody's grading you, and the very worst thing that can happen is that you and your friends will decide to let someone else DM for a while.

Resolving Actions
The second skill, resolving the players' actions, is a little more difficult to master, but it's still pretty straightforward. What makes this skill relatively easy to develop is a pair of powerful weapons that are at your disposal: the AD&D game rules and simple common sense.

Instructions for resolving many of the most common actions the players are bound to throw your way appear in the Player's Handbook and the DUNGEON MASTER Guide. The rules tell you how to resolve armed attacks and attempts to cast spells, to turn undead, to find secret doors, and so on. The rules also tell you how to resolve many of the consequences that might arise from a character's actions. A thief who fails to climb a wall falls. The rules tell you just how much the fall hurts the thief.

It is precisely because the rules are so helpful in resolving actions that a good working knowledge of the rules is a minimum requirement for any DM. Generally, each of the game rules exists because the specific situation it handles is particularly hard to resolve credibly without assistance. Take the earlier example of the thief falling off the wall. Does she die from the fall? Break a leg? Survive completely unscathed? Any ruling you might make based solely upon your own whim is bound to seem totally arbitrary to the players, risking your credibility. An arbitrary decision here or there is relatively easy to accept, but long strings of arbitrary decisions tend to make the players start to doubt the impact of their own actions. After a while, they'll find it hard to make intelligent decisions because they have no idea how you'll rule.

Using the rules whenever possible makes it easy to make some tough calls because the rules leave little for you to decide. The rules also provide a reliable mechanism by which the players can predict the outcome of some simple actions while still leaving a great deal to chance. It's this fact that allows the players to make informed, intelligent decisions. A party of 3rd-level adventurers usually knows that they shouldn't mess with an ancient red dragon because even a cursory knowledge of the game rules reveals that the dragon will soon be picking bits of adventurer out of its teeth. Without consistent rules, there would be no way for the players to decide when a monster is worth fighting.

For all of these reasons, to be a good DM you must know as much about the game rules as possible. If you're not aware of some rules (and there are an awful lot to digest), you might find yourself making arbitrary decisions when it isn't really necessary. Making matters a bit more complicated is the fact that simply knowing the rules is sometimes not enough. Under some circumstances, you have to understand the intent of the rules to wield them capably. A perfect example might be the rules for saving throws; their true potential is often overlooked. The DUNGEON MASTER Guide tells us that a saving throw vs. paralyzation, poison, or death magic might be used to represent an extreme test of a character's physical fortitude or willpower. Suppose the prototypical damsel in distress is trapped in a burning tower and one of the PCs decides to run in after her. Does the attempt succeed? If you hadn't carefully read the DUNGEON MASTER Guide you might be forced to make an arbitrary decision even though this is an ideal opportunity to simply call for a saving throw vs. paralyzation or death magic. If the saving throw is successful, the character rescues the damsel. If the saving throw is unsuccessful, the character is forced out of the building before he can rescue her. Of course, the fact that the rules are useful doesn't mean that you should become a slave to them. It's often more important to keep the game moving than to make sure you're following each rule strictly. This advice probably makes it sound like it's going to be difficult to determine when you should carefully follow the rules and when you should just "wing it," but you're likely to find that such decisions are surprisingly intuitive during play. You'll quickly develop a feel for which rules seem too complex for your group and which seem relatively digestible.

When it comes to resolving those actions that are not covered by the rules, common sense is your most useful ally. Once play begins, your players are going to throw all sorts of unexpected actions at you, and many won't be explicitly covered by the rules. It's at this point that you're forced to become both judge and jury. Do the actions seem plausible? What is their likely outcome? Suppose, for example, that the adventurers are trapped high up in a wizard's tower. To escape, they've decided to rip some bed sheets into strips so they can tie the strips together and fashion a crude rope. How long do you think it might take to fashion the rope and scale down? Unfortunately, the rules are of little use here.

The best way to beef up your ability to make this type of decision is to watch a lot of adventure movies and read a lot of fantasy novels. The last example illustrates an important point. You should never lose sight of the fact that the events that take place in your AD&D games are not supposed to reflect our own reality, but a world of grand adventure. In the real world it might be difficult and time consuming to shred bed linen into a useful rope. In movies and fantasy stories, though, the heroes do this sort of thing all the time. As a consequence, the tactic should work perfectly well in your games. The more stories you read and absorb, the better the feel you'll develop for handling these situations. Fortunately, few DMs have to be specially motivated to read fantasy stories and watch adventure films. If you're interested in the AD&D game, the odds are good that you're also interested in the stories that inspired it.

Revealing Information
The third and most difficult skill to develop is a good feel for when and how you should reveal information. Suppose that the adventurers hear a cry of distress coming from around the corner, deep in a dungeon. When you describe the cry, should you reveal that the voice sounds like that of the damsel the adventurers rescued from the burning tower a couple of sessions ago, or should you reveal that information only if one of the players specifically asks if the voice sounds familiar? Unfortunately, there's no easy answer to this dilemma.

These situations generally reduce down to a trade-off between revealing lots of information to keep the game moving and revealing only a little information to force the players to make more decisions and ask for more clarifications. Expert DMs tend to use the amount of information they reveal at any given time to pace their adventures in the same way that great movie directors control the pacing of their films. Consider a simple example: The adventurers have just entered an unpopulated dungeon chamber filled with various bits of broken furniture. Beneath an old shattered bed is a small sack containing 10 gold pieces. There are several ways you might describe this scene, each revealing various bits of information.

Method One
You enter a small chamber filled with broken bits of old furniture. From the doorway you can see what appears to be a small sack resting beneath an old shattered bed.

In this case, you're revealing everything. To get the gold, the players simply announce their intention to grab the sack.

Method Two
You enter a small chamber filled with broken bits of old furniture.

Here, the gold is now one step removed. To find it, the players must announce a specific intent to search the broken furniture.

Method Three
You enter a small chamber. Inside is an old smashed chair, two badly broken tables, and the remains of shattered bed.

This method makes the gold even harder to find. Simply searching the furniture isn't really possible. To find the gold, the players must announce a specific intent to search beneath the shattered bed.

Which approach is best depends upon the situation. If this isn't an important encounter, and you want the game to move quickly past it, you might select the first or second approach. If this is a crucial encounter, though, you might opt for the third approach to slow things down a bit and emphasize the action. Notice how the amount of information you supply in your descriptions dictates the amount of detail the players are forced to supply in return. Unfortunately, the only reliable method of gaining a feel for which approach is appropriate at what times is to earn it through hard experience.

In addition to slowing down play, another reason why you might sometimes opt to reveal less information is to challenge the players to make decisions, take actions, or draw conclusions. Suppose a dusty room in your dungeon houses a giant spider living in a camouflaged web that stretches across the ceiling. Instead of immediately describing the web, you might describe a set of dusty footprints that lead into the middle of the room and suddenly stop. It's now up to the players to recognize that something must have dropped down to kill the owner of those footprints in the room's midst, prompting them to specifically examine the ceiling and find the hidden web. If the players don't grasp the significance of the disappearing footprints and simply blunder into the room, you might rule that the spider takes them by surprise, putting them in a bit of a pickle. This is a great example of the sort of "puzzle" you should try to incorporate into your games. (See issue #266.) Deliberately withholding some information is often a necessary component of making such puzzles work.