Added CriticalHitEvent to allow more control over whether a attack is a critical or not, and what damage it does.

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

@@ -120,6 +120,7 @@ import net.minecraftforge.event.entity.living.LivingSetAttackTargetEvent;
 import net.minecraftforge.event.entity.living.LootingLevelEvent;
 import net.minecraftforge.event.entity.player.AnvilRepairEvent;
 import net.minecraftforge.event.entity.player.AttackEntityEvent;
+import net.minecraftforge.event.entity.player.CriticalHitEvent;
 import net.minecraftforge.event.entity.player.PlayerEvent;
 import net.minecraftforge.event.entity.player.PlayerInteractEvent;
 import net.minecraftforge.event.world.BlockEvent;
@@ -1259,6 +1260,18 @@ public class ForgeHooks
         return errored;
     }
 
+    @Nullable
+    public static CriticalHitEvent getCriticalHit(EntityPlayer player, Entity target, boolean vanillaCritical, float damageModifier)
+    {
+        CriticalHitEvent hitResult = new CriticalHitEvent(player, target, damageModifier, vanillaCritical);
+        MinecraftForge.EVENT_BUS.post(hitResult);
+        if (hitResult.getResult() == Event.Result.ALLOW || (vanillaCritical && hitResult.getResult() == Event.Result.DEFAULT))
+        {
+            return hitResult;
+        }
+        return null;
+    }
+
     private static void setActiveModContainer(ModContainer mod)
     {
         if (Loader.instance().getLoaderState() != LoaderState.NOINIT) //Unit Tests..

src/main/java/net/minecraftforge/event/entity/player/CriticalHitEvent.java

@@ -0,0 +1,100 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+package net.minecraftforge.event.entity.player;
+
+import net.minecraftforge.fml.common.eventhandler.Event.HasResult;
+import net.minecraftforge.fml.common.eventhandler.Cancelable;
+import net.minecraftforge.common.MinecraftForge;
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.player.EntityPlayer;
+
+/**
+ * This event is fired whenever a player attacks an Entity in
+ * EntityPlayer#attackTargetEntityWithCurrentItem(Entity).<br>
+ * <br>
+ * This event is not {@link Cancelable}.<br>
+ * <br>
+ * This event has a result. {@link HasResult}<br>
+ * DEFAULT: means the vanilla logic will determine if this a critical hit.<br>
+ * DENY: it will not be a critical hit but the player still will attack<br>
+ * ALLOW: this attack is forced to be critical
+ * <br>
+ * This event is fired on the {@link MinecraftForge#EVENT_BUS}.
+ **/
+@HasResult
+public class CriticalHitEvent extends PlayerEvent
+{
+    private float damageModifier;
+    private final float oldDamageModifier;
+    private final Entity target;
+    private final boolean vanillaCritical;
+    
+    public CriticalHitEvent(EntityPlayer player, Entity target, float damageModifier, boolean vanillaCritical)
+    {
+        super(player);
+        this.target = target;
+        this.damageModifier = damageModifier;
+        this.oldDamageModifier = damageModifier;
+        this.vanillaCritical = vanillaCritical;
+    }
+    
+    /**
+    * The Entity that was damaged by the player.
+    */
+    public Entity getTarget()
+    {
+        return target;
+    }
+    
+    /**
+    * This set the damage multiplier for the hit.
+    * If you set it to 0, then the particles are still generated but damage is not done.
+    */
+    public void setDamageModifier(float mod)
+    {
+        this.damageModifier = mod;
+    }
+    
+    /**
+    * The damage modifier for the hit.<br>
+    * This is by default 1.5F for ciritcal hits and 1F for normal hits .
+    */
+    public float getDamageModifier()
+    {
+        return this.damageModifier;
+    }
+
+    /**
+    * The orignal damage modifier for the hit wthout any changes.<br>
+    * This is 1.5F for ciritcal hits and 1F for normal hits .
+    */
+    public float getOldDamageModifier()
+    {
+        return this.oldDamageModifier;
+    }
+    
+    /**
+    * Returns true if this hit was critical by vanilla
+    */
+    public boolean isVanillaCritical()
+    {
+        return vanillaCritical;
+    }
+}