Biomes

A biome lock does not stop a player walking in. It makes the place unsurvivable — effects, damage, a warning, and interactions refused — until the stage opens.

{
  "biomes": {
    "biomes": [
      "minecraft:desert",
      "#minecraft:is_forest"
    ]
  }
}

Entries are biome ids, or biome tags with a # prefix. Everything else about the behaviour is server-wide rather than per entry.

In the editor

The Biomes tab on a stage, with a searchable picker over every biome and biome tag the pack has loaded.

The behaviour itself is not on this tab — it is server-wide, and lives in the Common tab of the Config Editor under biome_lock.

What happens while a player stands there

All of it is configured once, in [biome_lock], and applies to every locked biome in the pack:

Setting	Default
effectsEnabled / effects	on / blindness 30s	Potion effects applied while inside. Written as "effect_id, seconds, amplifier".
clearEffectsOnLeave	false	Clear them the moment the player leaves rather than letting them run out.
messageEnabled / messageFormat / showInChat	on	A periodic warning. {stage} and {biome} are replaced.
damageEnabled / damageAmount / damageInterval	on / 1.0 / 20	Periodic damage.
blockRightClick / blockLeftClick / blockProjectiles	all on	Interactions refused inside.
blockExplosions	on	Explosions do not destroy blocks inside.
checkInterval	10	Ticks between position checks. Range 1–200.

Note that damage is on by default for biomes and off by default for structures — a structure is something you are kept out of, a biome is something you cannot live in.

The catch: biomes are large and irregular

A structure has walls. A biome does not — its edge wanders, it interlocks with its neighbours, and in 1.21 it varies with height as well as position. A player standing near a border can cross it without meaning to, and the check runs every checkInterval ticks rather than continuously.

In practice this means a biome lock reads as "this whole region is hostile", not as a precise boundary. If you need a precise boundary — a walled city, a crater, one side of a river — draw a zone instead. A zone has exact edges, can carry a hard barrier that cannot be crossed at all, and can have rules of its own rather than the pack-wide ones above.

Global or individual

Both. A player is always standing in the biome when the question is asked, so there is someone to check against.

See also

• Dimensions & Structures — the same toolkit around a structure.
• Zones — precise areas with their own rules.
• gameplay.toml — the full settings block.
• Complete Examples