Monster Room

The monster room is a small building in the Overworld where a monster spawner that produces either zombies, skeletons or spiders is found in the middle of a room with cobblestone lateral walls and cobblestone mixed with mossy cobblestone floors.

Generation[]

Monster rooms generate naturally in the Overworld terrain in any biome uncommonly and always nearby caves, ravines, underwater ravines, aquifers, abandoned mineshafts and strongholds. Each chunk has fourteen attempts to generate monster rooms underground within y-coordinates 0 to 320 or -58 to -1, each altitude range with different uniformity. For the higher altitude Y levels 0 to 320, up to 10 monster rooms can generate, while up to 4 monster rooms can generate in lower altitude Y levels -58 to -1. It is possible, though unlikely, for multiple attempts to succeed. In Bedrock Edition, monster rooms can generate as underground structures above sea level.

Monster rooms are a feature instead of a structure, so they generate regardless of whether the "Generate structures" world creation option has been toggled off for said world.^[1] They also cannot be searched by the /locate command.^[2]

For each attempt, a location (the position for monster spawner) and size (an open area with a width and length of 7 or 9 and a height of 6) is chosen. The attempt succeeds if the following conditions are met:

Blocks in the floor area (including under the walls) of the potential monster room must be material solid.
Blocks in the ceiling area (including over the walls) of the potential monster room must be material solid. The ceiling blocks may be gravity-affected such as gravel or sand, which fall if disturbed by the player.
The walls of the potential monster room must have 1–5 openings (2-high air blocks) at floor level. Monster rooms are always connected to a cavern or other hollow structure, although it is possible for the monster room itself to overwrite most of a tiny cave.

If the location passes, air and cobblestone are placed, then 3 attempts are made to generate each of two chests. To generate a chest, the chosen block must be empty and must have a solid block on exactly one of its four sides. The monster spawner is placed at the center of the monster room.

The monster spawner has a 50% chance of producing zombies, a 25% chance of producing skeletons, or a 25% chance of producing spiders. A zombie monster spawner in Bedrock Edition also has the same chance (5%) of producing zombie villagers as in natural generation.

Cobblestone has a 75% chance to be mossy when it is on the floor of the monster room.

You can use the command /place feature minecraft:monster_room ~ ~ ~ to generate a monster room only when you are under the specific location where the monster room could be found naturally.

Construction[]

Monster rooms are small rooms made of cobblestone and mossy cobblestone and contain a monster spawner and up to 2 chests. Finding a monster room without a chest is unlikely but possible. Additionally, there is a rare chance of a monster room being found without a monster spawner. Occasionally, a monster room generates with its chests in such a way as to create a double chest. Monster rooms generate with either a zombie (50% chance), skeleton (25% chance), or spider (25% chance) monster spawner. The monster spawner is always in the center of the monster room room, with chests located around the walls of the room (large chests can connect with the short side against the wall). Each block of the floor has a 25% chance of being cobblestone and a 75% chance of being mossy cobblestone.

Because the horizontal range for spawning mobs is 4 blocks from the monster spawner, it is possible for mobs to be spawned outside the walls of a 5×5 monster room that is surrounded by air outside the walls.

Loot[]

GodSpawner — An example of monster room chest loot in *Java Edition*.

In Java Edition, each monster room chest contains items drawn from 3 pools, with the following distribution:

Item	Stack Size ^[A]			Weight ^[B]			Chance ^[C]	Avg. per chest ^[D]	Avg. # chests to search ^[E]
Item	1–3×	1–4×	3×	1–3×	1–4×	3×	Chance ^[C]	Avg. per chest ^[D]	Avg. # chests to search ^[E]
Bone	—	—	1–8	—	—	¹⁰⁄₄₀	57.8%	3.375	1.7
Gunpowder	—	—	1–8	—	—	¹⁰⁄₄₀	57.8%	3.375	1.7
Rotten Flesh	—	—	1–8	—	—	¹⁰⁄₄₀	57.8%	3.375	1.7
String	—	—	1–8	—	—	¹⁰⁄₄₀	57.8%	3.375	1.7
Wheat	—	1–4	—	—	²⁰⁄₁₂₅	—	34.1%	1.000	2.9
Bread	—	1	—	—	²⁰⁄₁₂₅	—	34.1%	0.400	2.9
Name Tag	1	—	—	²⁰⁄₁₂₉	—	—	27.9%	0.310	3.6
Saddle	1	—	—	²⁰⁄₁₂₉	—	—	27.9%	0.310	3.6
Coal	—	1–4	—	—	¹⁵⁄₁₂₅	—	26.6%	0.750	3.8
Redstone Dust	—	1–4	—	—	¹⁵⁄₁₂₅	—	26.6%	0.750	3.8
Music Disc (13)	1	—	—	¹⁵⁄₁₂₉	—	—	21.5%	0.233	4.6
Music Disc (cat)	1	—	—	¹⁵⁄₁₂₉	—	—	21.5%	0.233	4.6
Iron Horse Armor	1	—	—	¹⁵⁄₁₂₉	—	—	21.5%	0.233	4.6
Golden Apple	1	—	—	¹⁵⁄₁₂₉	—	—	21.5%	0.233	4.6
Beetroot Seeds	—	2–4	—	—	¹⁰⁄₁₂₅	—	18.5%	0.600	5.4
Melon Seeds	—	2–4	—	—	¹⁰⁄₁₂₅	—	18.5%	0.600	5.4
Pumpkin Seeds	—	2–4	—	—	¹⁰⁄₁₂₅	—	18.5%	0.600	5.4
Iron Ingot	—	1–4	—	—	¹⁰⁄₁₂₅	—	18.5%	0.500	5.4
Bucket	—	1	—	—	¹⁰⁄₁₂₅	—	18.5%	0.200	5.4
Enchanted Book^[F]	1	—	—	¹⁰⁄₁₂₉	—	—	14.7%	0.155	6.8
Golden Horse Armor	1	—	—	¹⁰⁄₁₂₉	—	—	14.7%	0.155	6.8
Gold Ingot	—	1–4	—	—	⁵⁄₁₂₅	—	9.6%	0.250	10.4
Diamond Horse Armor	1	—	—	⁵⁄₁₂₉	—	—	7.6%	0.078	13.2
Music Disc (otherside)	1	—	—	²⁄₁₂₉	—	—	3.1%	0.031	32.6
Enchanted Golden Apple	1	—	—	²⁄₁₂₉	—	—	3.1%	0.031	32.6

In Bedrock Edition, each monster room chest contains items drawn from 3 pools, with the following distribution:

Item	Stack Size ^[A]			Weight ^[B]			Chance ^[C]	Avg. per chest ^[D]	Avg. # chests to search ^[E]
Item	1–3×	1–4×	3×	1–3×	1–4×	3×	Chance ^[C]	Avg. per chest ^[D]	Avg. # chests to search ^[E]
Bone	—	—	1–8	—	—	¹⁰⁄₄₀	57.8%	3.375	1.7
Gunpowder	—	—	1–8	—	—	¹⁰⁄₄₀	57.8%	3.375	1.7
Rotten Flesh	—	—	1–8	—	—	¹⁰⁄₄₀	57.8%	3.375	1.7
String	—	—	1–8	—	—	¹⁰⁄₄₀	57.8%	3.375	1.7
Wheat	—	1–4	—	—	²⁰⁄₁₂₅	—	34.1%	1.000	2.9
Bread	—	1	—	—	²⁰⁄₁₂₅	—	34.1%	0.400	2.9
Name Tag	1	—	—	²⁰⁄₁₂₉	—	—	27.9%	0.310	3.6
Saddle	1	—	—	²⁰⁄₁₂₉	—	—	27.9%	0.310	3.6
Coal	—	1–4	—	—	¹⁵⁄₁₂₅	—	26.6%	0.750	3.8
Redstone Dust	—	1–4	—	—	¹⁵⁄₁₂₅	—	26.6%	0.750	3.8
Music Disc (13)	1	—	—	¹⁵⁄₁₂₉	—	—	21.5%	0.233	4.6
Music Disc (cat)	1	—	—	¹⁵⁄₁₂₉	—	—	21.5%	0.233	4.6
Iron Horse Armor	1	—	—	¹⁵⁄₁₂₉	—	—	21.5%	0.233	4.6
Golden Apple	1	—	—	¹⁵⁄₁₂₉	—	—	21.5%	0.233	4.6
Beetroot Seeds	—	2–4	—	—	¹⁰⁄₁₂₅	—	18.5%	0.600	5.4
Melon Seeds	—	2–4	—	—	¹⁰⁄₁₂₅	—	18.5%	0.600	5.4
Pumpkin Seeds	—	2–4	—	—	¹⁰⁄₁₂₅	—	18.5%	0.600	5.4
Iron Ingot	—	1–4	—	—	¹⁰⁄₁₂₅	—	18.5%	0.500	5.4
Bucket	—	1	—	—	¹⁰⁄₁₂₅	—	18.5%	0.200	5.4
Enchanted Book^[F]	1	—	—	¹⁰⁄₁₂₉	—	—	14.7%	0.155	6.8
Golden Horse Armor	1	—	—	¹⁰⁄₁₂₉	—	—	14.7%	0.155	6.8
Gold Ingot	—	1–4	—	—	⁵⁄₁₂₅	—	9.6%	0.250	10.4
Diamond Horse Armor	1	—	—	⁵⁄₁₂₉	—	—	7.6%	0.078	13.2
Music Disc (otherside)	1	—	—	²⁄₁₂₉	—	—	3.1%	0.031	32.6
Enchanted Golden Apple	1	—	—	²⁄₁₂₉	—	—	3.1%	0.031	32.6

↑ ^a ^b The size of stacks (or for unstackable items, number) of this item on any given roll.
↑ ^a ^b The weight of this item relative to other items in the pool.
↑ ^a ^b The odds of finding any of this item in a single chest.
↑ ^a ^b The number of items expected per chest, averaged over a large number of chests.
↑ ^a ^b The average number of chests the player should expect to search to find any of this item.
↑ ^a ^b All enchantments are equally probable, including treasure enchantments (except Soul Speed, and Swift Sneak), and any level of the enchantment is equally probable.

Data values[]

ID[]

Java Edition:

Configured feature	Identifier
[No displayed name]	`monster_room`

Bedrock Edition:

Feature	Identifier
[No displayed name]	`[No ID]`

History[]

Java Edition Infdev
20100625-2					Added dungeons. The chests may contain gunpowder, strings, wheat, bread, iron ingots, buckets, saddles and rarely golden apples.
Java Edition Alpha
v1.0.4					Added redstone dust to dungeon chests, sometime between its introduction in Alpha v1.0.1 and 1.0.4.^{[is this the correct version?]}
v1.0.14					Added the newly introduced 13 and cat music discs to dungeon chests.
Java Edition Beta
1.4					Added cocoa beans to dungeon chests.
Java Edition
1.4.6		12w49a			Added enchanted books to dungeon chests.
1.6.1		13w16b			Added name tags to dungeon chests.
1.6.1		13w18a			Added horse armor to dungeon chests and removed cocoa beans. Probabilities have now also been adjusted.
1.7.2		13w36a			Changes in cavern generation now make dungeon considerably rarer.^[3]
1.8		14w30a			The chances of music discs in dungeon chests have been reduced.
1.9		15w44a			Added bones, coal, rotten flesh, enchanted golden apples, and melons, pumpkins and beetroot seeds to dungeon chests.
					The average yield of music discs in dungeon chests has been increased.
					The average yield of enchanted books, gunpowder and string in dungeon chests have been doubled.
					The average yield of normal golden apples in dungeon chests has been substantially increased.
					The average yield of iron horse armor in dungeon chests has been decreased.
					The average yields of name tags, saddles, wheat and bread in dungeon chests have been nearly halved.
					The average yields of iron ingots and buckets in dungeon chests have been substantially decreased.
1.14		18w43a			Renamed "Dungeon" to "Monster Room".
1.14		18w43a			Create New World screen still mentions it as "dungeon".
1.16		?			As a result of a world generation bug fix, monster room positions have been shifted.
1.17		?			Monster room generation has changed - it appears they are again capable of generating in open air areas such as cliffsides like they were prior to 1.7.2.
1.18		21w40a			Monster rooms now generate more frequently, especially below Y=0.
1.18.2		22w03a			Monster rooms can now be placed using `/placefeature`.
1.19		22w18a			Due to the removal of placefeature command, monster rooms now instead be placed using `/place`.
1.19.4		23w05a			Removed mentioning of monster rooms from the Create New World screen. Before this snapshot, a contradiction existed in Java Edition that even though the "Generate Structures" world creation option listed "dungeons" as an example structures that were supposed to generate only when the option was turned "ON", monster rooms generated even if the option was set to "OFF".
Pocket Edition Alpha
v0.9.0		build 1			Added dungeons.
v0.15.0		build 1			Added name tags, enchanted books and horse armor to dungeon chests.
Bedrock Edition
1.2.0		beta 1.2.0.2			Added music discs to dungeon chests.
1.17.0		?			The probability of dungeons had been changed to less common to match Java Edition.
1.18.0		beta 1.18.0.21			Dungeons now generate more frequently, especially below Y=0.
Legacy Console Edition
TU1	CU1	1.0	Patch 1	1.0.1	Added dungeons.
New Nintendo 3DS Edition
0.1.0					Added dungeons.

Issues[]

Issues relating to "Monster Room" are maintained on the bug tracker. Report issues there.

Gallery[]

A gravel ore feature fallen into a monster room.
A rare instance of a monster room generating in midair.
A spider monster room.
A chest in a monster room that is open, revealing loot.
A zombie monster room.
Loot reveal.
A monster room next to a cave.
Skeleton monster spawner in badlands mineshaft.
A monster room full of skeletons without bows.
A dungeon with a torch.
A dungeon with zombies.

Surface monster rooms[]

A caved in surface monster room.
A surface monster room.
Monster rooms can rarely be found open to the surface.
A monster room found under a frozen ocean.
A monster room found in the water.
Two surface monster rooms right next to each other.
A surface monster room in the PC Gamer Demo Edition.
Monster rooms generated underneath sand tend to cause cave-ins.
A zombie monster room at ground level.
A monster room on the surface.

Multiple monster rooms[]

Five monster rooms and 2 cave spider monster spawners close together in a mineshaft, cleared to show all 7 monster spawners.
A double monster room, the wall of the first acting as the entrance of the second.
A double monster room with three chests.
A triple monster room.
Extremely rare double-decker monster room.
A monster room in a monster room.
Triple monster room around the village.

Odd generation[]

A monster room intersecting with an abandoned mineshaft.
A monster room found by an end portal room in a stronghold.
Monster room generated aside the chest chamber of the temple. One chest was overwritten by the monster room wall.
A monster room distorted by a desert temple.
A monster room with lava spilling into it from a spring.
A monster room distorted by a cave system.
A monster room that has become flooded because of falling sand on the bottom of a river.
Igloo basement touching this monster room without 1 jail beside of the torch.
A monster room intersecting with a mineshaft at bedrock level.
A monster room connected to a dead end of an abandoned mineshaft.
A monster room with a waterfall flowing into it.
A monster room generating without the monster spawner and the chests in a desert temple.
A monster room with no chests.
A double chest monster room.
A monster room intersecting a mineshaft.
A zombie monster room that generated in a stronghold.
A monster room, mineshaft and stronghold are in one area.
Floating monster room without a floor.
Monster room with a geode underneath it, causing the chest to generate on the top of smooth basalt.
A monster room that spawned intersecting a mineshaft, where one of the chests has been replaced with a minecart chest.
A monster room next to a mineshaft.
Another monster room next to a mineshaft.
Zombie monster room connected to a mineshaft.
A zombie monster room intersecting with an ancient city.