Damage and Status Effects

Damage events

// Block any single hit over 100 damage
mod.events().register(EntityEvents.ALLOW_DAMAGE, (entity, damage) -> damage.amount() < 100);

// Halve magic damage
mod.events().register(EntityEvents.MODIFY_DAMAGE, (entity, damage) ->
        damage.type().equals(ResourceId.minecraft("magic")) ? damage.amount() / 2 : damage.amount());

mod.events().register(EntityEvents.DIED, (entity, cause) ->
        LOGGER.info("{} died ({})", entity.name(), cause.type()));

Event	Listener	Meaning
ALLOW_DAMAGE	(LivingEntityView, DamageInfo) -> boolean	false cancels the damage
MODIFY_DAMAGE	(LivingEntityView, DamageInfo) -> float	Changes the damage amount
DIED	(LivingEntityView, DamageInfo) -> void	After death

DamageInfo has type() (the damage type ID), amount(), and attacker(). All of them are called on the server thread.

• Modifying the amount: For damage that ALLOW_DAMAGE did not cancel, listeners change the amount in registration order. If it drops to 0 or below, the damage is cancelled.
• The game's damage handling is called again with the changed amount, so armor and resistance effects apply to the changed amount.

Dealing damage

living.hurt(5);                                         // generic damage; false if cancelled
living.hurt(ResourceId.of("my_mod", "zap"), 3);         // a data-defined damage type

Define damage types in the vanilla format in a data pack at data/<mod>/damage_type/<name>.json.

Status effects

mod.content().effect("glowing_heart", new EffectDefinition(EffectCategory.BENEFICIAL, 0xFFD54F, 20,
        (entity, amplifier) -> entity.setHealth(entity.health() + 1)));

living.addEffect(ResourceId.of("my_mod", "glowing_heart"), 100, 0);   // ticks, amplifier
living.hasEffect(ResourceId.minecraft("glowing"));

• EffectDefinition(category, color, tickInterval, behavior): the category, the color, how many ticks between actions, and the action (EffectBehavior.onTick)
• The action runs on the server thread.
• The effect icon is assets/<mod>/textures/mob_effect/<name>.png.