Attribute Base Modifier

Attribute Base Modifier (ABM) allows you modify the default base value of any attribute of any mob.

This mod is server-side.

Side	Required to install
Dedicated server	True
Integrated server	True
Single-player client	True
Pure client	False

This mod is data-driven. It's recommended to read Data pack – Minecraft Wiki if you encounter issue.

You can define multiple rules in the data pack to apply modifiers.

Register Rules

Rules are registered by JSON files in the data pack.

The rule file should be in data/<namespace>/abm_rules/<name>.json.

If the rule is successfully registered, its ID will be <namespace>:<name>.

Like other data pack contents, all rules will be reloaded when the server reloads data. Specifically, when reload the world or use reload command.

JSON format:

• <root> Compound{}
  • include Compound{} A include filter. Only the type specified here will be included. Optional, all type of mobs will be included if omitted.
    • type String* | *Array[] List the mobs that need to be included.
      • String either an ID or a tag(starts with #). e.g. minecraft:zombie, #minecraft:undead.
    • spawn_group String This means all mobs of this spawn group is included. Must be one of monster, creature, ambient, water_creature, underground_water_creature, water_ambient, misc, or axolotls. Has no effect when coexists with type.
  • exclude Compound{} A exclude filter. The format is the same as include. Optional, no mobs will be excluded if omitted.
  • modifies Array[] Defines the modification methods.
    • Compound{} Define an attribute and the modification methods. If the mob lacks default value of this attribute, this modification will be skipped.
      • attribute String ID of the attribute . e.g. minecraft:max_health.
      • modifiers Array[] The modification methods. The base values are calculated sequentially in order.
        • Compound{} A modification method.
          • type String The type of modification(operator). Must be one of set, add or multiply.
          • value Number The value of this modification. Will be parsed as a double value.
  • default_enable Boolean Whether to enable this rule by default. See "Debug Command" for more information. Optional, defaults to true.

Example: (some IDs may be not correct)

{
    "include": {
        "spawn_group": "monster"
    },
    "exclude": {
        "type": "#c:bosses"
    },
    "modifies": [
        {
            "attribute": "minecraft:max_health",
            "modifiers": [
                {
                    "type": "add",
                    "value": 100
                }
            ]
        },
        {
            "attribute": "minecraft:armor",
            "modifiers": [
                {
                    "type": "set",
                    "value": 10
                }
            ]
        }
    ]
}

Here is an example_data_pack.

Debug Command

abmrule <rule_id> [enable|disable]

You can enable or disable a rule by this command.

This command is for debugging.

When the rule is reloaded, this state will be reset to its default value. Specifically. the default_enable defined in the rule's JSON file.

FAQ

• Some mob is not modified after reload the rules using reload command.

This is an expected behavior.

After a reload, a previously summoned mob may not update its default attributes unless it's "recreated" in the code (typically when mob's chunk is loaded).

However, it's recommended to summon a new mob to reduce uncertainty and ensure it has the latest default attributes.

If you want a previously summoned mob updates, it's recommended to re-enter the world.

• How to define rules before creating a world, just like a config?

In certain situations, such as when making mod packs, many people encounter this problem.

It's recommended to make a global data pack through a low-code mod or Paxi.