@SubscribeEvent
public void onAttackEntity(LivingAttackEvent event)
{
    World world = event.entity.getEntityWorld();
    if (event.source.getEntity() instanceof EntityPlayer)
    {
        EntityPlayer player = (EntityPlayer) event.source.getEntity();
        int extraDmg = 0;
        if (player.getHeldItem().getTagCompound().hasKey("attrDamage"))
            extraDmg += player.getHeldItem().getTagCompound().getInteger("attrDamage");
        playerConfig.addServerMessage("EXTRA DMG: " + extraDmg);
        event.entityLiving.hitByEntity(event.source.getEntity());
        event.entityLiving.setHealth(0); // Just for Test...
        event.setCanceled(true);
    }
}