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.
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