Minecraft trial chambers are copper-and-tuff dungeons buried deep underground. You find one with a Buried Trial Chambers Map from a journeyman cartographer (12 emeralds and a compass), or with /locate structure trial_chambers. Beat the trial spawners for trial keys, open the vaults, then drink an ominous bottle and do it all again for ominous keys. Ominous vaults are the only source of the heavy core you need for a mace.
Every number below comes from the Minecraft Wiki loot tables and Mojang’s own Java changelogs. All of it was checked on November 5, 2026 against Java 26.3, the current release. Nothing about trial chambers has changed in the 26.4 snapshots so far.
Table of Contents
Quick answer
- Where: underground in every Overworld biome except the deep dark. The starting room sits between Y=-40 and Y=-20.
- How to find one: buy a Buried Trial Chambers Map from a journeyman cartographer, look in the secret chest at an abandoned camp, or use
/locatein a world with cheats on. - Trial key: each trial spawner you clear has a 50% chance to drop one. It opens one normal vault.
- Ominous trial key: drink an ominous bottle first. Each ominous spawner you clear then has a 30% chance to drop a key, which opens one ominous vault.
- Heavy core: 7.5% per ominous vault. Craft it with a breeze rod to make a mace.
- Breeze rods: 1-2 per breeze. Breezes only spawn in trial chambers.
An ominous vault on its candle altar. You need an ominous trial key and active Trial Omen to open it. Image: Mojang Studios
How to find Minecraft trial chambers
Mojang’s 1.21 notes call trial chambers “a relatively common find throughout the Deepslate layer”. According to the wiki, the game places one in every 34×34-chunk region on a grid centred on X=0, Z=0. The only exception is a region where a deep dark biome cancels it. Trial chambers are also one of the few structures that generate in the same places in Java and Bedrock, so a shared seed gives the same chamber locations on both.
| Method | What you need | Notes |
|---|---|---|
| Cartographer trade | 12 emeralds + 1 compass | A journeyman-level trade. Every map from the same cartographer points to the same chamber. |
| Abandoned camp secret chest | Find an abandoned camp | New in Java 26.3 (Wilderness Bound). The secret chest holds one of seven explorer map types, and Trial Chambers is one of them. The wiki lists Bedrock support from 26.50. |
/locate structure trial_chambers |
Cheats on | The same structure ID works in Java and Bedrock (Java also accepts minecraft:trial_chambers). |
| Caving at Y -40 to -20 | Time | Look for copper and tuff bricks showing in cave walls. The wiki notes exposed caves around a chamber often have odd shapes. |
Java 26.3 also renamed the item. The old “Trial Chambers Explorer Map” is now the Buried Trial Chambers Map. It’s now its own item with its own icon, and you can no longer zoom it out. Bedrock got the same name in 26.60, according to the wiki. For other cartographer trades, see our Minecraft villager trades chart.
What’s inside: spawners, mobs and the breeze
When a chamber generates, it picks one mob from each category for its trial spawners. Every chamber has the breeze, but not every chamber gets all four categories.
| Category | Possible mobs |
|---|---|
| Breeze | Breeze (always) |
| Melee | Husk, spider or zombie |
| Ranged | Bogged, skeleton or stray |
| Small melee | Baby zombie, cave spider, silverfish or slime |
A trial spawner switches on when a Survival or Adventure player comes within 14 blocks and in line of sight. A normal spawner sends 6 mobs, plus 2 more for each extra player. A breeze spawner sends only 2 breezes (plus 1 per extra player), one at a time. Once everything is dead, the spawner ejects loot for each player and then goes on a 30-minute cooldown. The cooldown keeps ticking even when you leave the area.
What a normal trial spawner drops:
| Drop | Chance |
|---|---|
| Trial key (drops for every player) | 50% |
| Bread (1-3) | 15% |
| Cooked chicken | 15% |
| Baked potato (1-3) | 10% |
| Potion of Regeneration | 5% |
| Potion of Swiftness | 5% |
Trial keys also turn up in entrance chests (6.8%) and corridor decorated pots (2.8%), according to the wiki. Chamber entrances have a hopper on top of a barrel. Mojang added these in 1.21.2 so you can dump junk before a fight.
Trial keys vs ominous trial keys
| Trial key | Ominous trial key | |
|---|---|---|
| Comes from | Trial spawners (50%), entrance chests, corridor pots | Ominous trial spawners only (30%) |
| Opens | Normal vault (normal flames) | Ominous vault (soul flames) |
| Extra requirement | None | You must still have the Trial Omen effect when you use it |
| Vaults per chamber | In rooms with spawners, plus the entrance room | About 6-8 on average |
| Uses per player | Once per vault | Once per vault |
Each vault keeps a list of up to 128 players who have opened it, so you can open each vault once and every friend gets their own turn. In Java, a renamed key won’t open a vault (bug MC-268183), so don’t put your keys through an anvil.
Vault loot: what a normal vault gives
A vault ejects 2-5 stacks from three pools: common, rare and unique. The rare pool is the big Java vs Bedrock difference. In Java a vault has an 80% chance to roll it, in Bedrock only 20%. The unique pool rolls 25% of the time in both. The vault cycles through items while it waits, but the item on display doesn’t tell you what you’ll get, so timing your click won’t help.
| Item | Java chance per vault | Bedrock chance per vault |
|---|---|---|
| Emeralds (2-4) | 38.4% | 39.7% |
| Wind charges (1-3) | 24.0% | 29.6% |
| Ominous bottle (I-II) | 16.5% | 20.6% |
| Diamonds (1-2) | 8.5% | 10.7% |
| Golden apple | 8.3% | 8.3% |
| Enchanted book (Mending, Riptide, Loyalty, Channeling or Impaling) | 7.0% | 1.7% |
| Enchanted book (Sharpness, Bane of Arthropods, Efficiency, Fortune, Silk Touch or Feather Falling) | 7.0% | 1.7% |
| Enchanted crossbow | 7.0% | 1.7% |
| Bolt armor trim | 6.2% | 6.2% |
| Music disc “Precipice” | 4.2% | 4.2% |
| Guster banner pattern | 4.2% | 4.2% |
| Enchanted diamond chestplate / axe | 3.5% each | 0.9% each |
| Trident | 2.1% | 2.1% |
The unique pool (golden apple, Bolt trim, Precipice, Guster pattern, trident) is the same in both editions. The gear and books are where Java players do much better. For what those books are worth, see our Minecraft enchantments list, and for the Bolt template see our armor trims list.
Drinking an ominous bottle near a trial spawner turns Bad Omen into Trial Omen and starts an ominous trial. Image: Mojang Studios
Ominous bottles: how to start an ominous trial
An ominous bottle gives you Bad Omen for 100 minutes (Mojang: “1 hour and 40 minutes”). It comes in levels I to V. You can get them three ways:
- Raid captains: a pillager captain killed outside a raid always drops one, level I-V.
- Normal vaults: level I-II, 16.5% in Java and 20.6% in Bedrock.
- Ominous vaults: level III-V, 13.9%.
When a trial spawner sees you with Bad Omen, the effect turns into Trial Omen, which lasts 15 minutes for each Bad Omen level. A level I bottle gives you 15 minutes and a level V bottle gives you 75 minutes. The level doesn’t make the fight harder, it only gives you more time. Any spawner within 15 blocks that can see you turns ominous, skips its cooldown if its last run wasn’t ominous, and despawns the mobs it already had.
Don’t drink milk during the run. Milk clears Trial Omen, and you need Trial Omen to open an ominous vault. A totem of undying clears it too, and so does dying.
What changes in an ominous trial
- Mobs spawn in chainmail, iron or diamond helmets and chestplates, all with Protection IV, Fire Protection IV and Projectile Protection IV. In Java they don’t drop this armor.
- Melee mobs carry iron or diamond swords and ranged mobs get bows, sometimes with Power I or Punch I.
- Spiders, silverfish and other mobs that can’t wear gear come in double numbers instead.
- Every 8 seconds the spawner drops projectiles from above onto you and its own mobs. Each spawner uses a set of two. One is always a lingering potion (Wind Charged, Oozing, Weaving, Infested, Strength, Speed or Slow Falling), and the other is an arrow, poison or slowness arrow, small fireball or wind charge.
What an ominous trial spawner drops: ominous trial key 30%, baked potato (2-4) 21%, steak (1-2) 21%, golden carrot (1-2) 14%, Potion of Regeneration 7%, Potion of Strength 7%. After its 30-minute cooldown it goes back to being a normal spawner.
Ominous vault loot (heavy core and more)
You’ll know an ominous vault by the small altar of red candles and red glazed terracotta around it. There’s one in every combat chamber, plus more at the ends of corridors and in some intersections. It ejects 2-5 stacks. The unique roll happens 75% of the time and always comes out first.
| Item | Chance per ominous vault |
|---|---|
| Emeralds (4-10) | 56.2% |
| Wind charges (8-12) | 47.4% |
| Arrows of Slowness IV (4-12) | 37.5% |
| Diamonds (2-3) | 26.4% |
| Enchanted golden apple | 22.5% |
| Flow armor trim | 22.5% |
| Flow banner pattern | 15.0% |
| Ominous bottle (III-V) | 13.9% |
| Block of emerald | 13.8% |
| Enchanted crossbow / block of iron | 11.0% each |
| Enchanted diamond axe / chestplate | 8.3% each |
| Heavy core | 7.5% |
| Music disc “Creator” | 7.5% |
| Wind Burst I book | 5.5% |
| Breach or Density book | 5.5% |
| Book with Knockback, Punch, Smite, Looting or Multishot | 5.5% |
| Block of diamond | 2.8% |
The wiki gives one table for both editions. Mojang’s 1.21 changelog lists the two banner patterns the other way round (Flow in vaults, Guster in ominous vaults). The wiki’s current loot tables put Guster in normal vaults and Flow in ominous vaults, and that’s what we’ve used here.
A mace smash attack in a trial chamber. The heavy core for it only comes from ominous vaults (7.5%). Image: Mojang Studios
The breeze and mace route
This is our suggested order, built from the numbers above. The facts come from the wiki and Mojang. The plan is ours.
- Gear up. Bring iron armor or better, a shield, food and building blocks. Arrows bounce off breezes, so use melee or wind charges against them.
- Clear the chamber normally. Collect trial keys (50% per spawner) and open every normal vault. Java’s 80% rare roll makes this step worth more in Java than in Bedrock.
- Farm breeze rods. A breeze has 30 HP. It shoots wind charges from up to 16 blocks, jumps up to 15 blocks sideways and drops 1-2 breeze rods (more with Looting) plus 10 XP. One breeze rod crafts into 4 wind charges. Breeze spawners only sit in combat chambers, usually in the middle of the room, and refill after 30 minutes.
- Bank your ominous bottles. Keep any you get from vaults or raid captains. A level V bottle gives the longest window (75 minutes of Trial Omen).
- Do the ominous run. Drink a bottle near a spawner and clear the ominous waves. Each one has a 30% chance at an ominous key. Open each ominous vault before Trial Omen runs out.
- Craft the mace. Put the heavy core directly above a breeze rod in the crafting grid. At 7.5% per vault, the wiki works out about 13 ominous vaults per heavy core on average. With 6-8 per chamber, plan on roughly two chambers’ worth.
Once you have it, Mojang’s numbers for the smash attack are +4 damage per block for the first 3 blocks fallen, +2 per block for the next 5, then +1 per block. Wind charges launch you up for the fall. Density, Breach and Wind Burst are all in the ominous vault table. Our Minecraft mace guide covers the enchantments and damage in full.
Trial chambers are also built mostly from copper blocks and tuff bricks. If you’re planning a sorting room afterwards, our copper golem guide covers the build.
FAQ
What Y level are trial chambers at?
The starting room generates between Y=-40 and Y=-20, in the deepslate layer. The rest of the structure branches out from there.
Can you reopen a vault in Minecraft?
Not with the same player. Each vault remembers up to 128 players. Only after 128 other players have opened it does the first name drop off the list. Every new player can open every vault once.
Why won’t my ominous trial key open the ominous vault?
You need the Trial Omen effect active when you use the key. If it ran out, or you drank milk, drink another ominous bottle and let a trial spawner see you. In Java, a renamed key also won’t work.
Do trial spawners respawn?
Yes. After you clear one it goes on a 30-minute cooldown, and the timer keeps running while you’re away. A normal spawner that cooled down can also go ominous straight away if you come back with Bad Omen.
Are trial chambers the same in Java and Bedrock?
They’re in the same locations and have the same mobs, but the vault loot differs. Java vaults roll the rare pool 80% of the time, against 20% in Bedrock.
Sources: Minecraft Wiki (via its API): Trial Chambers, Vault, Ominous Vault, Trial Key, Ominous Trial Key, Trial Spawner, Ominous Trial Spawner, Ominous Trial, Ominous Bottle, Breeze, Heavy Core and Explorer Map; Mojang’s Java changelogs (launcher feed): Java 1.21 Tricky Trials, Java 1.21.2 and Java 26.3 Wilderness Bound. Checked November 5, 2026.
Live: Follow today’s gaming news as it happens
Featured image: Mojang Studios
