Add Synergy Modifier

MODIFIERS.md

@@ -224,6 +224,10 @@ These effects are applied when hurting enemies.
 **id:** `soulbound` | **crafting:** `minecraft:nether_star` ![nether_star](https://raw.githubusercontent.com/anish-shanbhag/minecraft-api/master/public/images/items/nether_star.png)
 
 **Decription:** Grants 15% bonus damage and mining speed when wielded by the original owner.
+### Synergy
+**id:** `synergy` | **crafting:** `minecraft:echo_shard` ![echo_shard](https://raw.githubusercontent.com/anish-shanbhag/minecraft-api/master/public/images/items/echo_shard.png)
+
+**Decription:** Gains 8% bonus damage for each other modifier on this tool.
 ### Withering
 **id:** `wither` | **crafting:** `minecraft:wither_rose` ![wither_rose](https://raw.githubusercontent.com/anish-shanbhag/minecraft-api/master/public/images/items/wither_rose.png)
 

src/main/java/dev/marston/randomloot/loot/modifiers/ModifierRegistry.java

@@ -67,6 +67,7 @@ public static Modifier getModifier(String name) {
 	public static Modifier PUMMELING = register(new Pummeling());
 	public static Modifier HAILEYS_WRATH = register(new HaileysWrath());
 	public static Modifier EARLY_BIRD = register(new EarlyBird());
+	public static Modifier SYNERGY = register(new Synergy());
 
 	// Biome-restricted modifiers
 	public static Modifier AQUATIC = register(new Aquatic());
@@ -103,7 +104,7 @@ public static Modifier getModifier(String name) {
 	public static final Set<Modifier> BREAKERS = Set.of(EXPLODE, LEARNING, ATTRACTING, VEINY, MELTING, EXCAVATOR, PROSPECTOR, MUNCHIES, FRAGILE, LUMBERING);
 	public static final Set<Modifier> USERS = Set.of(TORCH_PLACE, DIRT_PLACE, FIRE_PLACE, FIRE_BALL, VOID_TOUCHED);
 	public static final Set<Modifier> HURTERS = Set.of(CRITICAL, CHARGING, FLAMING, COMBO, DRAINING, POISONOUS,
-			WITHERING, BLINDING, BEZERK, NEMESIS, SOULBOUND, SCORCHED, FROZEN, OVERGROWN, FIERCE, FEASTING, EXECUTIONER, CROWD_PLEASER, PUMMELING, HAILEYS_WRATH, MUNCHIES, CHAOTIC, FRAGILE, CLUNKY, EARLY_BIRD);
+			WITHERING, BLINDING, BEZERK, NEMESIS, SOULBOUND, SCORCHED, FROZEN, OVERGROWN, FIERCE, FEASTING, EXECUTIONER, CROWD_PLEASER, PUMMELING, HAILEYS_WRATH, MUNCHIES, CHAOTIC, FRAGILE, CLUNKY, EARLY_BIRD, SYNERGY);
 	public static final Set<Modifier> HOLDERS = Set.of(HASTY, ABSORBTION, FILLING, RAINY, ORE_FINDER, SPAWNER_FINDER,
 			LIVING, REGENERATING, RESISTANT, FIRE_RESISTANT, AQUATIC, HUNTER, FEASTING, NATURALIST, CLUNKY);
 

src/main/java/dev/marston/randomloot/loot/modifiers/hurter/Synergy.java

@@ -0,0 +1,122 @@
+package dev.marston.randomloot.loot.modifiers.hurter;
+
+import dev.marston.randomloot.loot.LootItem;
+import dev.marston.randomloot.loot.LootItem.ToolType;
+import dev.marston.randomloot.loot.LootUtils;
+import dev.marston.randomloot.loot.modifiers.EntityHurtModifier;
+import dev.marston.randomloot.loot.modifiers.Modifier;
+import net.minecraft.ChatFormatting;
+import net.minecraft.core.particles.ParticleTypes;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.chat.MutableComponent;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.Level;
+
+import java.util.List;
+
+public class Synergy implements EntityHurtModifier {
+
+	private String name;
+	private static final float BONUS_PER_MODIFIER = 0.08f; // 8% per other modifier
+
+	public Synergy() {
+		this("Synergy");
+	}
+
+	public Synergy(String name) {
+		this.name = name;
+	}
+
+	public Modifier clone() {
+		return new Synergy();
+	}
+
+	@Override
+	public CompoundTag toNBT() {
+		CompoundTag tag = new CompoundTag();
+		tag.putString(NAME, name);
+		return tag;
+	}
+
+	@Override
+	public Modifier fromNBT(CompoundTag tag) {
+		return new Synergy(tag.getStringOr(NAME, "Synergy"));
+	}
+
+	@Override
+	public String name() {
+		return name;
+	}
+
+	@Override
+	public String tagName() {
+		return "synergy";
+	}
+
+	@Override
+	public String color() {
+		return ChatFormatting.LIGHT_PURPLE.getName();
+	}
+
+	@Override
+	public String description() {
+		return "Gains 8% bonus damage for each other modifier on this tool.";
+	}
+
+	@Override
+	public void writeToLore(List<Component> list, boolean shift) {
+		MutableComponent comp = Modifier.makeComp(this.name(), this.color());
+		list.add(comp);
+	}
+
+	@Override
+	public Component writeDetailsToLore(Level level) {
+		return null; // Dynamic bonus calculated per hit
+	}
+
+	@Override
+	public boolean forTool(ToolType type) {
+		return type.equals(ToolType.SWORD) || type.equals(ToolType.AXE);
+	}
+
+	private float calculateBonus(ItemStack itemstack) {
+		// Count other modifiers on this tool (excluding self)
+		List<Modifier> modifiers = LootUtils.getModifiers(itemstack);
+		int otherModifiers = Math.max(0, modifiers.size() - 1); // -1 to exclude this modifier
+
+		return otherModifiers * BONUS_PER_MODIFIER;
+	}
+
+	@Override
+	public boolean hurtEnemy(ItemStack itemstack, LivingEntity hurtee, LivingEntity hurter) {
+		Level level = hurtee.level();
+
+		float bonusPercent = calculateBonus(itemstack);
+
+		if (bonusPercent > 0) {
+			float baseDamage = LootItem.getAttackDamage(itemstack, LootUtils.getToolType(itemstack));
+			float bonusDamage = baseDamage * bonusPercent;
+
+			if (hurter instanceof net.minecraft.world.entity.player.Player p) {
+				hurtee.hurt(hurter.damageSources().playerAttack(p), bonusDamage);
+			} else {
+				hurtee.hurt(hurter.damageSources().mobAttack(hurter), bonusDamage);
+			}
+
+			// Visual feedback - purple particles when synergy activates
+			if (!level.isClientSide()) {
+				Modifier.TrackEntityParticle(level, hurtee, ParticleTypes.ENCHANT);
+			}
+		}
+
+		return false;
+	}
+
+	@Override
+	public boolean compatible(Modifier mod) {
+		// Synergy works with everything!
+		return true;
+	}
+}

src/main/resources/data/randomloot/recipe/trait_synergy.json

@@ -0,0 +1,8 @@
+{
+  "type": "randomloot:trait_change",
+  "item": {
+    "count": 1,
+    "id": "minecraft:echo_shard"
+  },
+  "trait": "synergy"
+}