Add a cancellable event that gets fired when a Totem of Undying is used (#9069)

src/main/java/net/minecraftforge/common/ForgeHooks.java

@@ -138,6 +138,7 @@ import net.minecraftforge.event.entity.living.LivingFallEvent;
 import net.minecraftforge.event.entity.living.LivingHurtEvent;
 import net.minecraftforge.event.entity.living.LivingKnockBackEvent;
 import net.minecraftforge.event.entity.living.LivingSetAttackTargetEvent;
+import net.minecraftforge.event.entity.living.LivingUseTotemEvent;
 import net.minecraftforge.event.entity.living.LootingLevelEvent;
 import net.minecraftforge.event.entity.living.ShieldBlockEvent;
 import net.minecraftforge.event.entity.player.AdvancementEvent;
@@ -317,6 +318,11 @@ public class ForgeHooks
         return event;
     }
 
+    public static boolean onLivingUseTotem(LivingEntity entity, DamageSource damageSource, ItemStack totem, InteractionHand hand)
+    {
+        return !MinecraftForge.EVENT_BUS.post(new LivingUseTotemEvent(entity, damageSource, totem, hand));
+    }
+
     public static float onLivingHurt(LivingEntity entity, DamageSource src, float amount)
     {
         LivingHurtEvent event = new LivingHurtEvent(entity, src, amount);

src/main/java/net/minecraftforge/event/entity/living/LivingUseTotemEvent.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.event.entity.living;
+
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.damagesource.DamageSource;
+import net.minecraft.world.entity.LivingEntity;
+import net.minecraft.world.item.ItemStack;
+import net.minecraftforge.common.MinecraftForge;
+import net.minecraftforge.eventbus.api.Cancelable;
+import net.minecraftforge.fml.LogicalSide;
+
+/**
+ * Fired when an Entity attempts to use a totem to prevent its death.
+ *
+ * <p>This event is {@linkplain Cancelable cancellable}, and does not {@linkplain HasResult have a result}.
+ * If this event is cancelled, the totem will not prevent the entity's death.</p>
+ *
+ * <p>This event is fired on the {@linkplain MinecraftForge#EVENT_BUS Forge event bus},
+ * only on the {@linkplain LogicalSide#SERVER logical server}.</p>
+ */
+@Cancelable
+public class LivingUseTotemEvent extends LivingEvent
+{
+    private final DamageSource source;
+    private final ItemStack totem;
+    private final InteractionHand hand;
+
+    public LivingUseTotemEvent(LivingEntity entity, DamageSource source, ItemStack totem, InteractionHand hand)
+    {
+        super(entity);
+        this.source = source;
+        this.totem = totem;
+        this.hand = hand;
+    }
+
+    /**
+     * {@return the damage source that caused the entity to die}
+     */
+    public DamageSource getSource()
+    {
+        return source;
+    }
+
+    /**
+     * {@return the totem of undying being used from the entity's inventory}
+     */
+    public ItemStack getTotem()
+    {
+        return totem;
+    }
+
+    /**
+     * {@return the hand holding the totem}
+     */
+    public InteractionHand getHandHolding()
+    {
+        return hand;
+    }
+}