Damage Condition Types

A damage condition inspects an incoming damage source and its damage amount, and returns true or false. The source and the amount are supplied by whatever data table declares the condition, so the condition itself only describes what to check about the damage it is given.

Damage conditions are a Java (built-in) registry, so their type ids are fixed and a data pack cannot add new ones. type selects the built-in type and its value is one of the ids tabulated on this page, written with the mxt namespace. A data pack never adds or removes entries in this registry. Only Java code or the KubeJS bridge can introduce custom condition types — see the KubeJS API.

In the table below, a field name followed by ? is optional; every other listed field must be present. The Fields column lists the JSON keys taken directly from the type's codec.

Common Structure

A condition is a JSON object whose type field names the built-in type. All remaining keys are the fields declared by that type.

{
  "type": "mxt:damage_type_tag",
  "tag": "minecraft:is_fire"
}

Because conditions are used as values inside other data tables, the same structure usually appears nested under a field such as damage_condition:

"damage_condition": {
  "type": "mxt:amount_range",
  "min": 4,
  "max": 20
}

Anywhere a damage condition is expected, an array of conditions is also accepted. The array is shorthand for mxt:and and passes only when every entry passes:

"damage_condition": [
  { "type": "mxt:projectile" },
  { "type": "mxt:amount_range", "min": 2, "max": 10 }
]

Damage Registries

damage_type accepts the id of a registered damage type, for example minecraft:fall, and damage_type_tag accepts a damage type tag such as minecraft:is_fire. Both follow the standard vanilla damage type registry, so data packs that add damage types or tags are visible here.

Datapack Visual Editor

The Datapack Visual Editor shows the field list of every type interactively, which is handy for checking a field name without reading the table here.

Condition Types

Type	Fields	Description
mxt:always_true	—	Always passes.
mxt:js	id, params?	Calls a damage condition handler that was registered through the KubeJS bridge.
mxt:and	conditions	Requires every nested damage condition to pass.
mxt:or	conditions	Passes when at least one nested damage condition passes.
mxt:not	condition	Negates a nested damage condition.
mxt:chance	chance	Passes randomly with the given probability between 0 and 1.
mxt:constant	value	Always returns the given boolean value.
mxt:amount_range	min, max	Checks that the damage amount lies between min and max.
mxt:directness	direct?	Checks whether the damage source has a direct entity independent of its owner; direct defaults to true, and false requires the opposite.
mxt:damage_type	damage_type	Matches one concrete registered damage type.
mxt:damage_type_tag	tag	Matches the damage source against a damage type tag.
mxt:fire	—	Matches damage that belongs to the vanilla fire damage tag.
mxt:magic	—	Matches vanilla damage sources that are classified as magic.
mxt:projectile	projectile?, projectile_condition?	Matches projectile damage, optionally restricted to one projectile entity type and filtered by an entity condition on the projectile.

Difference Between mxt:fire and a Damage Tag

mxt:fire takes no fields and is equivalent to mxt:damage_type_tag with the vanilla fire damage tag. Use the tag form when you want to point at a different tag without writing a new type.

Chance and Randomness

mxt:chance draws from the damage source entity's own random stream when the source has one, so the roll follows that entity rather than a fresh generator. When the source has no entity at all it falls back to a new unseeded random source, so that case is not reproducible across sides.