Biome Rules

Biome Rules

Biome rules define mob levels based on which biome they spawn in. They support both specific biome IDs and biome tags for broad matching.

Location

data/botzmobleveling/mob_levels/biomes/<rulename>.json

Basic Structure

{
  "biome": "minecraft:desert",
  "biome_tags": [],
  "priority": 50,
  "enabled": true,
  "level_range": {
    "min": 1,
    "max": 100
  },
  "level_mode": "distance",
  "fixed_level": null,
  "ignore_distance_scaling": false,
  "distance_multiplier": 1.0,
  "mob_overrides": {},
  "attribute_scaling": {}
}

Field Reference

Targeting Fields

Field	Type	Description
biome	String	Specific biome ID (e.g., minecraft:desert)
biome_tags	Array	List of biome tags for broad matching

Note: You can use biome, biome_tags, or both. If both are specified, the rule matches if either condition is met.

Optional Fields

Field	Type	Default	Description
priority	Integer	50	Higher values = higher priority
enabled	Boolean	true	Toggle this rule on/off
level_range	Object	{min: 1, max: 100}	Level range for random mode
level_mode	String	"distance"	One of: fixed, random, distance
fixed_level	Integer	null	Exact level (when mode is fixed)
ignore_distance_scaling	Boolean	false	Ignore distance from spawn
distance_multiplier	Double	1.0	Multiplier for distance-based levels
mob_overrides	Object	{}	Per-mob level overrides
attribute_scaling	Object	{}	Custom attribute bonuses

Biome Matching

Specific Biome

Match a single, specific biome:

{
  "biome": "minecraft:desert",
  "level_mode": "fixed",
  "fixed_level": 30
}

Biome Tags

Match multiple biomes using tags. Supports vanilla and modded biome tags:

{
  "biome_tags": [
    "minecraft:is_nether"
  ],
  "level_mode": "fixed",
  "fixed_level": 75
}

Combined Matching

Match both a specific biome AND biomes with certain tags:

{
  "biome": "minecraft:badlands",
  "biome_tags": [
    "minecraft:is_badlands"
  ],
  "level_range": {
    "min": 40,
    "max": 80
  }
}

Common Vanilla Biome IDs

Overworld

Biome	ID
Plains	minecraft:plains
Desert	minecraft:desert
Forest	minecraft:forest
Taiga	minecraft:taiga
Swamp	minecraft:swamp
Jungle	minecraft:jungle
Beach	minecraft:beach
Mountains	minecraft:stony_peaks
Ocean	minecraft:ocean
Deep Dark	minecraft:deep_dark

Nether

Biome	ID
Nether Wastes	minecraft:nether_wastes
Crimson Forest	minecraft:crimson_forest
Warped Forest	minecraft:warped_forest
Soul Sand Valley	minecraft:soul_sand_valley
Basalt Deltas	minecraft:basalt_deltas

End

Biome	ID
The End	minecraft:the_end
End Highlands	minecraft:end_highlands
End Midlands	minecraft:end_midlands
End Barrens	minecraft:end_barrens
Small End Islands	minecraft:small_end_islands

Common Biome Tags

Tag	Description
minecraft:is_overworld	All overworld biomes
minecraft:is_nether	All nether biomes
minecraft:is_end	All end biomes
minecraft:is_ocean	Ocean biomes
minecraft:is_deep_ocean	Deep ocean biomes
minecraft:is_forest	Forest biomes
minecraft:is_jungle	Jungle biomes
minecraft:is_badlands	Badlands biomes
minecraft:is_taiga	Taiga biomes
minecraft:is_hill	Hilly biomes
minecraft:is_mountain	Mountain biomes
minecraft:has_structure/village_plains	Biomes that can have plains villages

Complete Examples

Nether-Wide Rule

All mobs in the Nether get increased levels:

{
  "biome_tags": ["minecraft:is_nether"],
  "priority": 60,
  "level_mode": "distance",
  "level_range": {
    "min": 50,
    "max": 150
  },
  "distance_multiplier": 2.0,
  "attribute_scaling": {
    "minecraft:generic.max_health": {
      "base_bonus": 20.0,
      "per_level": 1.0,
      "operation": "addition"
    }
  }
}

Desert Difficulty Spike

High-level skeletons in deserts:

{
  "biome": "minecraft:desert",
  "priority": 75,
  "level_mode": "fixed",
  "fixed_level": 1000,
  "ignore_distance_scaling": true,
  "mob_overrides": {
    "minecraft:skeleton": {
      "fixed_level": 1000,
      "attribute_scaling": {
        "minecraft:generic.max_health": {
          "base_bonus": 100.0,
          "per_level": 1.0,
          "operation": "addition"
        },
        "minecraft:generic.attack_damage": {
          "base_bonus": 0.0,
          "per_level": 0.1,
          "operation": "multiply_base"
        }
      }
    }
  }
}

Ocean Progressive Difficulty

Deeper oceans = higher level mobs:

{
  "biome_tags": ["minecraft:is_ocean"],
  "priority": 50,
  "level_mode": "random",
  "level_range": {
    "min": 10,
    "max": 40
  }
}

{
  "biome_tags": ["minecraft:is_deep_ocean"],
  "priority": 55,
  "level_mode": "random",
  "level_range": {
    "min": 40,
    "max": 80
  }
}

Distance Scaling

By default, biome rules use distance scaling. This means:

1. Mobs near spawn get levels closer to level_range.min
2. Mobs far from spawn get levels closer to level_range.max
3. The distance_multiplier adjusts how fast levels increase

Disabling Distance Scaling

For fixed difficulty zones:

{
  "biome": "minecraft:deep_dark",
  "ignore_distance_scaling": true,
  "level_mode": "fixed",
  "fixed_level": 100
}

Priority with Structure Rules

Remember: Structure rules have higher default priority (100) than biome rules (50).

• A mob in a stronghold in a desert will use the stronghold rule
• To make biome rules take precedence, increase their priority above 100

{
  "biome": "minecraft:the_end",
  "priority": 150,
  "level_mode": "fixed",
  "fixed_level": 200
}

Tips

1. Use biome tags for broad rules (all nether, all oceans)
2. Use specific biomes for unique difficulty spikes
3. Distance scaling works well for gradual difficulty
4. Consider structure interactions when setting priorities
5. Test with the Nether - it's isolated from the overworld