Biome Modifications

dev.architectury.registry.level.biome.BiomeModifications

Change biome features and properties at load time - add mob spawns, place features, tweak climate or colors - across both loaders with one API.

The four phases

Modifications run in a fixed order so the result is predictable. Each phase has its own method:

Phase	Method	Use for
1. Add	addProperties	Adding new features/spawns to biomes.
2. Remove	removeProperties	Removing existing features/spawns.
3. Replace	replaceProperties	Swapping existing features for new ones.
4. Post-process	postProcessProperties	Final tweaks after everything else.

You aren't strictly required to use each phase for its named purpose, but doing so keeps the ordering predictable when multiple mods modify the same biome.

Applying a modification

Each method takes a BiConsumer<BiomeContext, BiomeProperties.Mutable>, and optionally a Predicate<BiomeContext> to select which biomes to affect. Without a predicate, the modification applies to every biome.

// Add a mob spawn to every forest biome:
BiomeModifications.addProperties(
    context -> context.hasTag(BiomeTags.IS_FOREST),     // which biomes
    (context, properties) -> {
        // mutate `properties` here
    });

BiomeContext

The BiomeContext tells you about the biome being modified:

• getKey() - the biome's Identifier (optional).
• getProperties() - read-only view of the current properties.
• hasTag(TagKey<Biome>) - whether the biome is in a given tag.

BiomeProperties.Mutable

The second argument lets you read and change the biome's climate, effects, generation settings, and spawns. Those property objects come from Architectury's biome hooks - see Biome Hooks for the full surface of BiomeProperties.