Trial Chambers

Trial chambers^{[note 2]} are uncommon underground structures that serve as a mid-game combat challenge.^[1] They consist mostly of copper blocks and tuff bricks, and are the only place where trial spawners and vaults naturally generate. Trial chambers are also the only place where breezes spawn, whose breeze rods can be used to craft wind charges. Various materials such as heavy cores and certain armor trims are obtained exclusively by unlocking vaults in trial chambers. As it is the only source of breeze rods and heavy cores, the structure is also the only location where maces can be obtained.

Trial chambers can also be used to obtain copper bulbs without entering the Nether, and large quantities of copper blocks and their derivatives.

Most copper blocks found in trial chambers are waxed, preventing them from oxidizing. However, some unwaxed copper blocks can also generate due to a bug.

Ominous trials can also take place here through the Bad Omen effect. Bad Omen converts to Trial Omen, which causes all trial spawners to become ominous, making them more difficult and providing greater rewards.

Generation

Trial chambers generate underground in the Overworld. The starting room generates at an altitude of between Y=-40 and -20, but the structure is not restricted to those Y levels; the majority of the structure's rooms tend to generate between Y=-20 and 0.

The generation of trial chambers follows a grid of 34×34 chunk regions centered on the world origin (X=0, Z=0). There is always one trial chambers structure generated in each region at a random location, unless a deep dark biome cancels the generation of the trial chambers.

While the origin point of the structure (corridor_end) cannot generate within a deep dark biome, other parts of it can intersect a deep dark biome.

Trial chambers are one of the only structures that generate on the same locations on Java Edition and Bedrock Edition.

Locating

Trial chambers can be located using buried trial chambers maps, which can be obtained in two ways.

• Buried trial chambers maps are sold by journeyman-level cartographer villagers for 12 emeralds and a compass. The maps always point to the nearest trial chamber relative to the cartographer that does not already have a buried trial chambers map that points to it. All maps bought from the same cartographer always point to the same structure.
• Buried trial chambers maps can be found in loot of secret chests in abandoned camps. (see Abandoned Camps § Secret chests).

Trial chambers are buried underground, so exposed caves will usually have weird shapes that will determine the location of a trial chamber.

In Java Edition, a given villager always trades the same map, which is determined upon the trade unlocking.

Structure

The starting room of the structure is corridor/end. This room connects to a chamber and a section of a corridor. At the end of the section of a corridor, an intersection links to another chamber and another section of a corridor is generated, but this time it ends on the atrium, which then leads to the entrance room.

The structure then branches out from some corridor/straight pieces.

File structure

All trial chambers structures found below are located in the folder client.jar/data/minecraft/structure/trial_chambers‌^{[JE only]} or data/behavior_packs/vanilla/structures/trial_chambers‌^{[BE only]}.

Blocks

This is a list of blocks that can generate in trial chambers. Blocks listed with a tag indicated that they are present in trial chambers only in Java Edition are marked.

Components

Corridors

Trial chambers are composed of two corridors:

• a corridor going from the entrance room to the intersection, passing through four slices and the atrium;
• a corridor going from the intersection to the end room, passing through four slices.

The intersection connects both corridors, forming an L-shape. The intersection and the end room always lead to a chamber (see § Chambers), while slices have a probability to lead to a hallway (see § Hallways).

Entrance

The entrance generates at the end of one of the two corridors, passing through the atrium. Each entrance contains a "doorway" that consists of waxed oxidized copper blocks, including its cut copper and chiseled copper variants.

entrance_1 and entrance_2 include a vault, two entrance chests, and a platform containing either an oak, a mangrove, or a cactus; additionally, entrance_1 has a secret room containing a bed and a chest.

entrance_3 includes two vaults and three entrance chests.

Atrium

The atrium generates between the entrance and one of the corridor's slices.

Slices

Corridor slices, or straight pieces,^{[note 6]} are sub-structures that make up the corridors; they are generated on top of a tuff brick plate. Each of the two corridors has four slices, composed randomly.

Except for straight_1 and straight_8, all slices have a copper door:

• straight_2 and straight_5 generate a copper door on the lower level;
• straight_3 and straight_6 generate a copper door on the middle level;
• straight_4 and straight_7 generate a copper door on the upper level.

On average, each trial chamber has 6.29 (⁴⁴⁄₇) doors. These copper doors can either lead directly to a chamber, a hallway or nothing.^[3] Provided the latter case doesn't happen:

• lower level doors always lead to a descending spiral staircase (¹⁄₂ chance between lower_hallway_connector or trapped_staircase);
• upper level doors always lead to an ascending spiral staircase (upper_hallway_connector);
• middle level doors and these spiral staircases have a 97.48% chance to directly lead to a chamber, 2.44% chance to lead to a hallway piece, and 0.08% chance to directly lead to a dead-end (see § Hallways);
• any doors in any level, especially the spiral staircases leading to them in the case of upper and lower level doors, can also generate dead-end pieces as fallback pieces.

Both straight_6 and straight_8 generate with a trial spawner that can either spawn a melee, small melee or ranged mob (see § Mobs), but always never breezes. straight_7 generates with a hidden vault.

Slices can generate with various decorations such as flower pots, decorated pots, candles and corridor barrels (see § Decor). Slices can have addons, some of them generate with a trial spawner (that can either spawn a melee, small melee or ranged mob, but never breezes), a dispenser trap or a vault. Some slices cannot contain specific types of or all corridor addons.

End

The end room generates at the end of one of the two corridors. It always leads to one of these chambers with equal probability:

• chamber_1
• eruption
• assembly
• slanted

End rooms cannot lead to any other chamber, i.e. it excludes:

• chamber_2
• pedestal
• chamber_4
• chamber_8

End rooms always include an ominous vault. In addition to its ominous vault, end_2 also features a regular vault and an chest with intersection loot.

Intersections

The intersection is the room that connects both corridors. It always features a safer zone equipped with beds as well as an entrance to a chamber (rarely a hallway, see § Hallways for more information about the hallway generation rules.). In addition to that:

• intersection_1 and intersection_2 feature an ominous vault;
• intersection_2 and intersection_3 feature a barrel with loot;
• intersection_2 features a secret room with an additional bed and a decorated pot always containing 3 strings.^[4]

Hallways

Hallways are segments that connect corridors to chambers. When a copper door generates in a corridor, it (or, in the case of an upper or lower door, the spiral staircase that follows it; see § Slices) may lead to one of the following pieces:

• a chamber (97.48%);
• a hallway segment (1.14%);
• an encounter (0.41%);‌^{[Java Edition only]}
• a dead end (0.08%).

If the selected piece cannot be generated, the game attempts to generate a different piece. After a certain number of failed attempts, it defaults to generating a dead end.​ If the dead end itself cannot be generated, no piece is generated.^[3]

This process is then repeated at the end of each hallway segment or encounter. Furthermore, hallways never branch, meaning that every copper door found in corridors eventually leads to a single chamber, a dead end, or nothing.

Encounters

Encounters are hallway pieces that consist in "short challenges leading to a larger chamber".^[6] They contain a single trial spawner and a vault.

Chambers

Chambers are large combat rooms that contain multiple trial spawners and vaults, as well as one ominous vault. Chambers can be accessed in numerous ways:

• they have a chance to generate in corridor slices (chambers can generate straight from slices by middle level copper doors) and hallways, in this case, all chambers can generate;
• they can always generate in intersections, also in this case, all chambers can generate;
• additionally, assembly, chamber_1, eruption and slanted can generate in the end of corridor ends.

Each chamber design has several potential entrances, of which only one is connected to the rest of the structure. The remaining entrances are sealed with an entrance cap (see § Miscellaneous). Each potential entrance, including the sealed ones, generates a disposal consisting of a hopper placed above a barrel (see § Decor), allowing players to manage their inventory before entering a chamber.^[7]

Chamber_1 and Chamber_2

Pedestal

Chamber_4

Eruption

Assembly

Chamber_8

Slanted

Decor

These are decor that can generate in the corridors, especially in encounter_4. undecorated_pot can also generate in chamber_4.

Dispenser

Dispensers in this category are controlled by loot table dispensers/trial_chambers/chamber. (See § Chamber dispenser for loot table.)

Loot containers

Other loot containers that belong to categories trial_chambers/chests and trial_chambers/reward.

Trial spawners

Miscellaneous