The bulk of adventures will take place in dungeons. Dungeons are dangerous locations such as abandoned castles, ore hideouts, and dragon's lairs. The contents of each room of a dungeon are determined by the referee or the author of a pre-designed adventure. Most locations will be keyed to a description, which includes any important information. Dungeon locations typically contain some combination of monsters, treasure, and traps. They can contain all or none of these. Seeing in a dungeon usually requires a light source, such as a torch or Light spell. Blind characters suffer a -4 penalty on all "to-hit" rolls and saving throws.

To start with, all you really need is a dungeon level or two, populated with monsters, treasure, and perhaps a few traps, and a town nearby for the characters to rest up , recover, and buy (and sell) things between expeditions to the dungeon. You do not have to design the town in any great deal to begin with. Give your town an inn for the characters to stay between adventures, a tavern or two for meeting people and gathering information and rumors, a general store, and a temple where the characters can obtain healing for a price. You can add more places as needed, but these will be enough to start play.

If you are randomly determining the contents of rooms, chambers, caverns, etc. in a dungeon, the Dungeon Stocking Table can help. The result indicates what will be found in each room. Each result will also have a certain probability of being accompanied with treasure.

Dungeon Stocking Table

*You should think out a unique result carefully. This result could include special encounters or special areas that stand out from encounters in most other rooms.

Empty rooms should generally not be completely barren, they may contain all sorts of things that might interest, delay, or confuse explorers. While treasure in an empty room might be obvious (e.g. a silver cup stilling on a pedestal), it will more likely be hidden or mixed in with other items in the room.

If you are creating a large multi-level dungeon, monsters on a level should generally range from one HD below the dungeon’s level to one hit die above the dungeon level. Unique encounters may be an exception.

Traps: Traps are mechanical (and sometimes magical) hazards such as pit traps, poison needles, or magical wards concealed in a dungeon or attached to an object in a dungeon. When a character triggers a trap, they must make a saving throw or suffer the damage listed below. A successful save means the character suffers half damage. Thieves can use Find and Remove Traps special ability to detect and disarm traps. Magical traps suffer a -1 penalty to such attempts. Once a referee has determined whether a trap is magical or not, they must then decide whether the trap is Common, Dangerous, Lethal, or Deadly.

• Common Trap: The character suffers 1d6 points of damage, save for half.
• Dangerous Trap: The character suffers 3d6 points of damage, save for half.
• Lethal Trap: The character suffers 6d6 points of damage, save for half.
• Deadly Trap: If the character fails their saving throw, they die. Otherwise, no damage.