Minecraft Trial Chambers Guide: Find, Clear and Loot Them

Trial chambers are underground structures built from tuff bricks and copper, found between about Y=-40 and Y=-20 in almost every Overworld biome. Inside, trial spawners send waves of mobs at you, and beating them gives you trial keys that open vaults full of loot. The ominous version of the challenge is the only source of heavy cores for the mace.

Last checked: November 9, 2026. Spawn heights, spawner settings and loot odds below come from the Java 26.3 game files. The vault loot tables in Mojang's official Bedrock sample files use the same weights.

Where do trial chambers spawn?

Trial chambers are buried underground, so you usually find them by accident while caving or mining. The game data places each chamber's starting room between Y=-40 and Y=-20, and the structure spreads out from there.

Each 34-chunk region is 544 blocks across, so chambers are fairly common. If you mine at Y=-30 for a while, or explore large caves at that depth, you will probably break into one.

Look for these signs:

• Tuff bricks and polished tuff showing in a cave wall. Natural tuff is rough and gray, while the chamber's bricks have a clean, carved pattern.
• Copper blocks and copper grates, often oxidized green. These are waxed in the structure, so they do not change color over time.
• Copper bulbs giving off light deep underground.

With cheats on, /locate structure minecraft:trial_chambers gives you the coordinates of the nearest one.

How do trial spawners work?

A trial spawner is a special spawner that starts a fight when a player comes within 14 blocks. It spawns a set number of mobs, a few at a time. When every mob in the wave is dead, the spawner gives each player who took part a reward, then goes on a 30-minute cooldown.

The mobs depend on the spawner. The game data lists these groups:

Breeze spawners are the most dangerous. A normal one releases 2 breezes for a single player, plus 1 more for each extra player. Breezes fire wind charges that knock you around, so fight them on solid ground away from ledges.

What a spawner drops after you win:

Trial spawners cannot be mined for a drop, and they do not spawn new waves until the cooldown runs out.

What loot is in trial chamber vaults?

A vault is a locked block that takes a key. Normal vaults use a trial key and ominous vaults use an ominous trial key. Each player can open each vault once, so friends do not compete for loot.

A normal vault gives you three kinds of rolls:

• One main roll: 80% from the rare table (emeralds, enchanted bows and crossbows, iron or diamond gear, golden carrots, enchanted books including Mending), 20% from the common table.
• One to three common rolls: arrows, tipped arrows, emeralds, wind charges, iron ingots, honey bottles, ominous bottles and diamonds.
• A 25% chance at a special item: one of the five below.

Ominous vaults use stronger tables. The main roll can give emerald, iron or diamond blocks, enchanted diamond gear, Breach or Density books, and Wind Burst books. The common rolls give more emeralds, more wind charges and diamonds. The special roll fires 75% of the time:

The heavy core is the main reason people run ominous trials. The mace guide explains the recipe and how many vaults you should expect to open.

How do you start an ominous trial?

Ominous trials are a harder mode of the same structure:

1. Get an ominous bottle. Pillager captains, the pillagers carrying a banner, always drop one. Normal vaults sometimes include one too.
2. Drink it to get Bad Omen.
3. Enter the trial chamber. Bad Omen changes into Trial Omen.
4. Approach a trial spawner. Spawners near a player with Trial Omen turn ominous. Their mobs come better equipped, and the spawner also drops hazards on you during the fight, such as lingering potions.

Keep the Trial Omen running by moving from spawner to spawner. Each ominous spawner only rewards you once per cooldown, so a chamber with several spawners gives you several chances at an ominous key.

What should you bring?

• A shield. Skeletons, strays and bogged shoot often, and a shield blocks most of it. A bow still works well against these ranged mobs.
• Armor and a sword or axe. Iron is enough for normal trials. Diamond helps a lot for ominous ones.
• Food and a stack of blocks. Blocks let you wall off a flank or climb out of a pit.
• A plan for breezes. Breezes bounce arrows and most other projectiles back, so a bow is useless against them. Close the distance and hit them with a sword, axe or mace.
• A water bucket. Wind charges can launch you into a long fall.
• A pickaxe to tunnel into the chamber from a safe side.

You do not need to fight every spawner at once. Clear rooms one at a time, and back out of a fight if a second spawner wakes up.

Which advancements come from trial chambers?

Frequently asked questions

What Y level are trial chambers at?

Trial chambers start between Y=-40 and Y=-20, according to the game data. The rooms spread out from that point, so mining or caving around Y=-30 gives you the best chance to break into one.

How often do trial spawners reset?

A trial spawner goes on a 30-minute cooldown after you clear it. Until then it stays inactive and will not give another reward.

Can more than one player loot the same vault?

Yes. Each player can open each vault once with their own key, so a group of four can all loot the same vault.

What is the chance of a heavy core from an ominous vault?

The chance is 7.5% per ominous vault. The special reward roll fires 75% of the time, and the heavy core is 1 of 10 weight on that list.

How do you get an ominous trial key?

Clear an ominous trial spawner. In the game data, it gives an ominous trial key 3 times out of 10 and food or potions otherwise. You only get ominous spawners while you have the Trial Omen effect.

Do trial chambers spawn in every biome?

Almost. The game data allows them in nearly every Overworld biome, oceans and cave biomes included, but not in the deep dark.