Small doors are a Lair type dungeon feature that a character may 'inspect' (or merely approach) to open which will release a wave of monsters. There are a total of three waves of monsters that will be released, and when all waves have been released the next inspection will produce treasure.
A Lair of Large Kobolds (3 waves with 4 large kobolds each)
Kobold Shamans Lair (3 waves with 3 to 4 kobold shamans each)
Dwarf Lair (3 waves with 3 to 4 dwarfs each)
Leprechaun Lair (1 Leprechaun)
The treasure depends on monsters found in the Lair.
Kobold Lairs drop 3-5 weapons, mostly non cursed and with small bonuses (but there can also be cursed bad ones)
Kobold Shaman Lairs content spell books, scrolls, wands, etc.
Dwarf Lairs may content a few gems, armor, and typical dwarf weapons (not all at the same time)
Leprechaun Lairs will have a large amount of gold inside, sometimes a few gems or 1-3 staffs
- Before releasing a wave of monsters by 'inspecting' the door it is recommended to have full health if possible as dealing with multiple enemies all at once can be difficult.
- Before triggering a wave of creatures from the door ensure that you are off to the side so you are not surrounded by the emerging creatures
- Leave room for retreat! Waves of monsters can be very tough, and it is important to open the small door from a side that allows you to backtrack if things get tricky.
- Many wands and spells can target creatures in a line. Open the door and retreat and soon you'll have a train of monsters waiting in a nice line to be zapped.
- Caution! Approaching a closed small door will cause the door to open and its first wave of inhabitants to come spilling out, although this has a chance to be prevented by stealth or invisibility.
- Caution! Interacting with the door will cause a wave of inhabitants to be released even if the interaction is canceled.
- With the right timing, jumping over the space in front of a closed door can be a method of passing the door while preventing the door from triggering to be opened.
- Waz has provided a tip on his blog relating to doors: "For example, you may find a small room with a closed door... before you knock on the door it might be a good idea to drop some of your gems and see if they are actually gas bombs, so you can weaken the horde of monsters as they come out of the room."