When I subscribe to receive LivingAttackEvents, I don't get any events on the client end when a mob attacks the player. I get the events on the server in that case, though, and I get events on both ends when the player attacks a mob. Why is this happening?

 

Here's a minimal test mod to demonstrate this problem:

package com.example.examplemod;

import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.event.entity.living.LivingAttackEvent;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.common.Mod.EventHandler;
import net.minecraftforge.fml.common.event.FMLInitializationEvent;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;

@Mod(modid = ExampleMod.MODID, version = ExampleMod.VERSION)
public class ExampleMod
{
    public static final String MODID = "examplemod";
    public static final String VERSION = "1.0";
    
    @EventHandler
    public void init(FMLInitializationEvent event)
    {
    	MinecraftForge.EVENT_BUS.register(this);
    }
    
    @SubscribeEvent
    public void onLivingAttack(LivingAttackEvent event) {
	String victimName = event.getEntity().getDisplayName().getUnformattedText();
	if(!event.getEntity().worldObj.isRemote) {
		System.out.println("local - victim is " + victimName);
	} else {
		System.out.println("remote - victim is " + victimName);
	}
    }
}

 

And here's the output of the player fighting a zombie:

[22:52:43] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:43] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:43] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:43] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Zombie
[22:52:43] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:44] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:44] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:44] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:44] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Zombie
[22:52:44] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:45] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:45] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:46] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:46] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Zombie
[22:52:46] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:47] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:47] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:48] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:48] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Zombie
[22:52:48] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:49] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:49] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:49] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:49] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Zombie
[22:52:49] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:50] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:50] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:50] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:50] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Zombie
[22:52:50] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:51] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:51] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:52] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:52] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Zombie
[22:52:52] [Client thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:34]: remote - victim is Zombie
[22:52:53] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231
[22:52:53] [server thread/INFO] [sTDOUT]: [com.example.examplemod.ExampleMod:onLivingAttack:32]: local - victim is Player231

Note that there are no lines that say "remote - victim is Player231".

Because mobs ONLY process attacking on the server - players trigger the attack on both sides because the client player is by necessity the one that initiates the attack, i.e. via player input.

Okay. How should I work around that if I need to do stuff on the client when a mob attacks?

Send a packet.