Trigger and Cost Types

trigger_type

Trigger matchers decide which runtime events an ability or a breakthrough condition reacts to. Each built-in trigger is a fieldless matcher; the registry entry itself supplies the signal identifier it compares against.

type	Description
mxt:tick	A periodic entity tick
mxt:attack	The entity attacked another entity
mxt:hurt	The entity took damage
mxt:kill	The entity killed another entity
mxt:block_break	The entity broke a block
mxt:block_use	The entity used a block
mxt:item_use	The entity finished using an item
mxt:equip	The entity's equipment changed
mxt:death	The entity died
mxt:breakthrough	The entity completed a breakthrough
mxt:technique_stage	A learned cultivation technique reached a new level
mxt:js	A matcher a server script decides

{"type": "mxt:triggered", "triggers": [{"type": "mxt:item_use"}]}

None of the built-in triggers has additional fields.

mxt:js:

Field	Type	Default	Description
signal	Identifier	required	The signal this matcher listens to; subscriptions are indexed by it
id	String	required	Callback ID registered with MxtTriggers.matcher(...)
params	Object	{}	Arbitrary JSON passed to the callback

{"type": "mxt:triggered", "triggers": [{"type": "mxt:js", "signal": "example:pill_taken", "id": "example:on_pill"}]}

This is the only way a data pack can react to a custom signal id: raise it from a server script with MxtTriggers.publish, and either subscribe a script to it or declare this trigger on an ability or on a resource's breakthrough conditions. The callback only decides whether the signal that reached the subscription fires, so a missing callback never matches. See the KubeJS API Reference.

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cost_type

A cost can be checked and then consumed from a player.

type	Fields	Description
mxt:resource	resource, amount	Consumes a datapack resource from the player's resource attachment
mxt:item	items, amount	Consumes matching items from the player's inventory
mxt:js	id, params?	Checked and paid by a server script callback

mxt:resource:

Field	Type	Default	Description
resource	Holder<resource>	required	The resource to consume
amount	NumberProvider	required	Amount to consume; must evaluate to a finite positive number

mxt:item:

Field	Type	Default	Description
items	ItemMatcher	required	Which items may be consumed; see ItemMatcher
amount	NumberProvider	required	Number of matching items to consume, rounded up; a non-positive or non-finite result means the cost cannot be paid

{"type": "mxt:item", "items": "#minecraft:logs", "amount": 8}

mxt:js:

Field	Type	Default	Description
id	String	required	Callback ID registered with MxtCosts.register(...)
params	Object	{}	Arbitrary JSON passed to the callback

{"type": "mxt:js", "id": "example:quest_token", "params": {"count": 3}}

A script cost is checked and then paid on the server, and it needs a player: a cost that is not a resource cost makes the whole ability require one. The callback receives the payer and the params, not the ability's formula context, because Cost is evaluated with a player alone.

A costs array also accepts the plain {"id": ..., "amount": ...} shorthand, which is read as mxt:resource. The shorthand is kept for compatibility; new entries should write the type explicitly.

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