Monster Room



Dungeons are naturally generated structures that appear in the Overworld. They are small rooms made of Cobblestone and Moss Stone and contain a hostile Mob Spawner and up to 2 Chests. Finding a dungeon without a chest is very unlikely, but possible. Dungeons generate with either a zombie, skeleton, or spider spawner that can easily be deactivated by placing torches all around the spawner.

Anyone exploring a cavern should be wary of encountering a dungeon, as they are almost always connected to large caverns, and are very dangerous. Spider Jockeys can spawn here if either the spider spawner spawns a spider and at exactly the same instant, a skeleton spawns in the same place as the spider.

Dungeons do exist on peaceful mode, as they are generated with the map. Monster Spawners will still spawn mobs in peaceful mode, but the mobs will instantly despawn.

Properties
Dungeons are generated as a 5x5, 5x7, or 7x7 floor space surrounded by cobblestone and moss stone. Dungeons contain 0-2 chests (two chests may be adjacent, forming a large chest), unless they are overwritten by a cave or other structure, dungeons also contain a monster spawner, which can be used to make a mob spawner trap. It is also possible to find two dungeons joined together, with 2 spawners and 0-4 chests - although sometimes three can be found joined with 0-6 chests and 3 spawners.

It is possible to find a dungeon almost anywhere in the ground, but they rarely spawn high in the stone layer of a map. As dungeons can spawn almost anywhere, there have been reports of dungeons being generated in unusual locations resulting in abnormal circumstances such as without a floor or within lava or underwater as shown in the gallery below. This often results in adverse or even advantageous side effects. A common side effect of such an occurrence is partial generation of the dungeon resulting in the loss of chests or a spawner. Dungeons may also spawn in abandoned mine shafts, ravines, and even strongholds (although this is very rare).

The mob spawner acts as a guard for the loot, spawning endless mobs until the player can light up the room enough to stop new mobs from being spawned, or simply break the spawner itself. This is usually accomplished by placing a torch on and around the spawner. The mob spawner is always in the center of the dungeon room, with chests located around the walls of the room (large chests can connect with the short side against the wall). The chests contain randomly generated treasure that are placed in random slots.

There is a 50% chance the spawner will be a Zombie spawner, 25% chance of Skeletons, and 25% chance of Spiders (*Note: This is only relevant to spawners generated in dungeons).

Chest contents
Each dungeon chest block contains up to 8 item stacks, with the following distribution:

This information was obtained from Minecraft's code. The generation algorithm places one of these items in a random slot in the chest eight times, possibly overwriting items already placed.

Locating a Dungeon
A reliable way of locating dungeons is through listening, either for a large amount of noise from one kind of mob, or for ambience. Neither of these things are an exclusive trait of a dungeon, but they do mean that there is an unlit and unexplored area nearby, which may well be a dungeon, particularly in the case of frequent and similar mob noises.

Another good way of locating a dungeon is searching for moss stone inside of a cave, abandoned mine shafts, etc. this may be the fastest way to locate a dungeon. Another way is to look for newly placed cobblestone.

Tips

 * To defeat a dungeon, aside from the obvious method of fighting the monsters and lighting up the area, one can instead tunnel underneath it and destroy the spawner from below.
 * It is also possible to dig a tunnel above the dungeon and flood the area with lava, kill all of the mobs, then place torches to disable the spawner just as the last of the lava disappears. You can fill the entire dungeon with sand and/ or gravel. When the blocks that gravity applies to fall on top of the mobs, they will be crushed and killed. Once the room is filled, you can dig out the chest and loot it. You can also set a block of TNT above the spawner and prime the TNT, but doing so will destroy the spawner, and the dungeon cannot be used as mob grinder.
 * Digging around the sides of the dungeon will allow you to bypass the spawner and loot the chests directly without any risk of health loss.
 * A fast way to collect loot from the chest is to destroy the chest rather than removing the items from it. This way you collect all loot as well as the chest.
 * Torches can be placed directly on the monster spawner. Placing one on each side provides the same effect as placing a torch on the blocks adjacent to the spawner, without needing to be replaced when you mine the floor out for Moss Stone.
 * changing it to peaceful and get the chest is the most easy way

Trivia



 * Dungeons will still generate if the 'generate structures' option is toggled to off, even though they are claimed not to by the in-game description.
 * Dungeons are almost always connected to a cavern, and because the cavern can be as small as a single block of air, the dungeon could completely overwrite it, usually resulting in a dungeon with no entrance.
 * Rarely, a mushroom will appear in a dungeon on mossy cobblestone.
 * It is possible, though almost impossibly rare for a dungeon to be generated at bedrock level, thereby deleting the bedrock. In which case digging through the moss stone can lead into the Void.
 * Rarely, on peaceful, a monster spawner may spawn a monster that plays its sound file before it can despawn.
 * If a dungeon has fallen gravel or sand in it, then placing a torch on the spawner may not be sufficient to light up the entire area to prevent spawning.
 * It is rarely possible for a player to find a dungeon with two spawners and up to 4 chests. This only occurs when a 5x5 dungeon spawns within a 7x7 dungeon, since the dungeon will remove any blocks from the walls or floor that open into a cave, the walls of the smaller dungeon will be removed, resulting in a 7x7 floor space with one spawner in the middle, and a second spawner adjacent or diagonally adjacent to the first.
 * Double-chest dungeons as shown below may have chests that form a perpendicular barrier between the wall and spawner (an exception to this would be in 7x7 dungeons, in which the chest cannot reach the spawner):
 * The Moss Stone pattern on the dungeon floor seems to have a pattern, most noticeable with a 5x5 dungeon, where a 2x2 cube of moss stone lays in one corner. Unknown if this happens with 5x7 or 7x7 dungeons.
 * If a dungeon loads in two chunks and one regenerates (often causing a flat vertical wall), the dungeon can become partially generated. This can be found if one of the walls of the dungeon is not cobblestone, but rather stone. Sometimes, the partially generated dungeon will not have a spawner or a chest. Example of a partially generated dungeon
 * The contents of chests in dungeons appear to be based on the world seed.
 * If you are playing on peaceful in a skeleton dungeon, sometimes skeletons will shoot arrows before despawning.
 * Rarely, three chests can be found in a single generated dungeon, though this might be due to a generation bug.