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====== Adding a Damage Type (1.19.4+) ======

==== Introduction ====

Sometimes you may want to add a custom damage type to your mod, for example if you're adding a custom damaging fluid similar to lava or a block like a magma block. Since 1.19.4, the creation of new damage types has become data-driven, meaning they are created using JSON files. To use your custom damage type in code however, you're going to need to get its ''<yarn class_5321>'' and create a new ''<yarn class_1282>'' using it.
In this tutorial, the “tutorial” namespace is used as a placeholder. If you have a separate modid, feel free to use it instead.

==== Creating a Damage Type ====

First, create a json file for your custom damage type following the format [[https://minecraft.wiki/w/Damage_type|here]]. It should be placed in your mod's ''data'' folder in a new subfolder called ''damage_type''. For example:
<code json data/tutorial/damage_type/custom_damage_type.json [enable_line_numbers="true"]>
{
  "exhaustion": 0.1,
  "message_id": "custom",
  "scaling": "when_caused_by_living_non_player"
}
</code>

Our new custom damage type will now cause 0.1 [[https://minecraft.wiki/w/Hunger#Exhaustion_level_increase|hunger exhaustion]] each time a player takes damage of this type, and the if the damage is caused by a living, non-player source (like being hit by a Zombie), the amount of damage dealt will scale with the world's difficulty. You can see all possible keys and values on the [[https://minecraft.wiki/w/Damage_type|respective Minecraft wiki page]].

==== Getting our damage type in code ====

To actually use our new damage type in code, we need to get its ''<yarn class_5321>'' and use a method to get the corresponding ''<yarn class_1282>'' object. Let's create a new class to keep track of our custom damage types and store our helper method.
<yarncode java ModDamageTypes.java [enable_line_numbers="true"]>
public class ModDamageTypes {

    /* 
     * Store the class_5321 of our class_8110 into a new constant called CUSTOM_DAMAGE_TYPE
     * The class_2960 in use here points to our JSON file we created earlier.
    */
    public static final class_5321<class_8110> CUSTOM_DAMAGE_TYPE = class_5321.method_29179(class_7924.field_42534, new class_2960("tutorial", "custom_damage_type"));

    public static class_1282 of(class_1937 world, class_5321<class_8110> key) {
        return new class_1282(world.method_30349().method_30530(class_7924.field_42534).method_40290(key));
    }
}
</yarncode>

Our static method ''of'' allows us to get the ''<yarn class_1282>'' we need to actually use our custom damage type in code, as any methods that deal damage will typically take a ''<yarn class_1282>'' and not a ''<yarn class_8110>''. 

==== Using our damage type ====

Now let's use our custom damage type. In this example, lets pretend we have a custom ''Block'' that implements the ''<yarn method_9591>'' method, similar to the Magma Block. If you haven't created a Block yet, check out the [[tutorial:blocks|blocks tutorial]].
<yarncode java ExampleBlock.java [enable_line_numbers="true"]>
public class ExampleBlock extends class_2248 {

    public ExampleBlock (class_2251 settings) {
        super(settings);
    }
    
    public void method_9591(class_1937 world, class_2338 pos, class_2680 state, class_1297 entity) {
        if(entity instanceof class_1309) {
            entity.method_5643(ModDamageTypes.of(world, ModDamageTypes.CUSTOM_DAMAGE_TYPE), 1.0f);
        }
    }
}
</yarncode>
You'll notice that ''<yarn class_1297>#<yarn method_5643>'' takes a ''<yarn class_1282>'' and not a ''<yarn class_8110>'' as its first argument. This is why we use our helper method ''of'', to get a useable ''<yarn class_1282>'' of our custom damage type!

Now whenever a ``<yarn class_1309>`` steps on our custom block, they'll take 1 damage (half a heart) using our custom damage type! However, if you notice, when you die from our custom damage type, the death message will simply be "death.attack.custom"! That's no good. We need to provide a translation for when something dies of our custom damage type! Add an entry to your language file:
<code json en_us.lang>
{
    [...]
    "death.attack.custom": "%1$s died from a custom damage type!"
    [...]
</code>

If you did everything correctly, when you die of our custom damage type, you'll see a proper death message with your username!

==== Damage type tags ====

Some types of damage in Minecraft bypass armor, like the Wither potion effect, or drowning damage. If you want to make your custom damage type have effects like bypassing armor or not damaging witches, there are tags for this!
You can find a list of Minecraft's damage type tags in ''data/minecraft/tags/damage_type''. 
To add your custom damage type to one of these tags, create a new json file with the same name in your ''data/<namespace>/tags/damage_type'' folder. Note that this file should go in the ''minecraft'' namespace, **NOT** your mod's namespace! Now simply ensure your tag file does not replace the existing tag by adding the ''replace'' key, and add your custom damage type into it:
<code json data/minecraft/tags/damage_type/bypasses_armor.json [enable_line_numbers="true"]>
{
    "replace": false,
    "values": [
        "examplemod:custom_damage_type"
    ]
}
</code>
A list of the tags and their effects is as follows:
^ Tag Name                     ^ Effect                                                                                            ^ Notes ^
| always_hurts_ender_dragons   | Always deals damage to dragons, no matter where they're hit or during what phase (excludes dying) | |
| always_most_significant_fall | Counts a fall as always being the highest height when compared to other falls. | Unsure if this actually has a tangible in-game effect.((Has something to do with determining death message when falling out of the bottom of the world. Have yet to see the effect in testing)) |
| always_triggers_silverfish   | Always causes Silverfish to call for help from other Silverfish hiding in blocks                  | |
| avoids_guardian_thorns | Does not trigger the Thorns effect when attacking Guardians | |
| burns_armor_stands | Deals a flat 4.0 damage to armor stands | |
| bypasses_armor | Ignores all armor base protection value. Does not ignore Protection enchantments. | |
| bypasses_effects | Bypasses both Resistance effect and Protection enchantments, but not armor. | |
| bypasses_enchantments | Ignores all types of Protection enchantments, but not base armor protection. | |
| bypasses_invulnerability | Damages players who are invulnerable, such as in Creative or Spectator mode | |
| bypasses_resistance | Bypasses Resistance effect |  |
| bypasses_shield | Bypasses shield blocking | Damage types in this tag do not disable shields similar to how Axes do. |
| damages_helmet | Damages the helmet worn by the amount of the damage, and reduces entity's damage taken by 25%. | |
| ignites_armor_stands | Sets armor stands on fire or deals 0.15 extra damage if already on fire | |
| is_drowning | The player will be invulnerable to damage types in this tag if gamerule ''drowningDamage'' is ''false'' | |
| is_explosion | Affected by Blast Protection enchant. Does not destroy dropped Nether Stars. Does not explode End Crystals. Applies explosive knockback. Triggers TNT minecarts. Destroys frames and drops the item held in them at the same time. | |
| is_fall | The player will be invulnerable to damage types in this tag if gamerule ''fallDamage'' is ''false''. Fall damage immune entities will ignore damage types in this tag. Affected by Feather Falling enchant. | |
| is_fire | Affected by Fire Protection enchant. Does not destroy fireproof items (such as Netherite). Triggers TNT minecarts. Fire immune entities will ignore damage types in this tag. Causes Witches to drink Fire Resistance potions. | |
| is_freezing | Deals 5x damage to entities in ''freeze_hurts_extra_types'' entity tag (Strider, Blaze, Magma Cube). The player will be invulnerable to damage types in this tag if gamerule ''freezeDamage'' is ''false''. | |
| is_lightning | Causes Turtles to drop Bowls when killed by a damage type in this tag. | |
| is_projectile | Affected by Projectile Protection enchant. Causes Endermen to teleport when damaged by a damage type in this tag. | |
| no_anger | Does not anger wolves, zombified piglins, or endermen to their attacker if the damage type used is in this tag. | |
| no_impact | Does not trigger entity velocity updates. | |
| witch_resistant_to | Witches will take 85% less damage from damage types in this tag. | |
| wither_immune_to | The Wither is invulnerable to damage types in this tag. | |