TheoryCraft 101: The melee hit table

TheoryCraft101 is here to introduce the more hardcore aspects of theorycrafting in a more casual approach. Ever wondered what the deal is with hit rating? Is expertise giving you a bit of a headache? TheoryCraft 101 has all your answers and more, as we explore the depths of the melee hit table.

Back by popular demand, and loads of begging on my part, TheoryCraft 101 is here once again to teach you the ins and outs of the fickle little systems that drive World of Warcraft. Due to numerous requests, we'll be tackling one of the more complex systems within the game, the melee hit table. For all of the hate that armor penetration has taken for being "too mathy," melee hit honestly isn't any better. Caster hit is very simplistic. You have a specific chance to miss a mob, and getting more hit mitigates that amount. Melee hit holds very different values than that. Why just talk about it? Saying that it's complex is all well and good, but let's actually see it, shall we?

As a preface to every TheoryCraft 101 installment, this post is going to contain calculations, figures, theoretical values/situations and other math-related information that, at times, can get a bit confusing. I will always attempt to simplify everything to the best of my abilities and explain the information as clearly as possible. After reading, if you still have any questions about the topic, then just ask. I'll do my best to address every question that you may have.

The auto attack table

To the left is the attack table which dictates every melee swing made by players, pets and mobs within the game. Every attack made generates an internal roll on the server, much like doing a /roll 100, that is then compared against this list. The list itself is displayed in order of precedence. In this case, precedence means that each item at the top of the list will occur before any item at the bottom of the list. That is to say, the server will first check against your chance to miss, then dodge, parry and so on until it gets to the end of the list. It should also be mentioned that every result is mutually exclusive to any other result. This means, you cannot get a blocked critical hit, nor a glancing critical hit. A hit will either be blocked, glancing or a crit. There are some cases where a specific result can be set to 0%. Beyond gearing (which can reduce miss, dodge and parry to 0), there are several situations which can also change the chance of some results:

• Only attacks made by players and pets can be glancing blows; an NPC is not capable of landing a glancing blow.

• Only NPCs are capable of landing a crushing blow; players and pets will never be able to land a crushing attack.

• Mobs cannot parry or block attacks made behind them.

• Players cannot dodge, parry or block attacks made behind them.

• There is 0.5-yard grace distance to determine whether an attacker is behind a target or not, in which all attacks occur from the front even if the attacker is technically standing behind the target.

• Incapacitated targets cannot dodge, parry or block attacks.

As stated, once an attack roll is made, the resultant is then compared against each possible outcome on the list. The list of possibilities continues until it reaches 100%. If the possible outcomes reach 100% before the end of the list, then all remaining possibilities are negated. Predominately, this will only occur when dealing with tanks, although there are certain debuffs in the game that can cause an the same result (such as the Choking Gas Bombs during the Professor Putricide encounter). There is also a phenomenon known as the crit cap, which will be discussed later.

Chance to miss

Every attack made has a certain chance to miss the target. This chance isn't directly related to level, but rather is a check against the attack skill of the player/mob and the defense skill of the player/mob. Although you will have a higher chance to miss against targets that are a higher level than you, it is because all mobs innately have all of their "skills" maxed and each new level raises the cap of each skill. There are four different formulae for determining your base chance to miss a target, depending on the target that you are attacking and the weapon style that you are using. If the difference between your weapon skill and the target's defense skill is equal to or less than 10 (mobs two levels higher than you or less,) then your base chance to miss will be as follows:

If the difference between your weapon skill and the target's defense skill is greater than 10 (mobs three levels higher than you or more), then your base chance to miss will be as follows:

Using these formula, you would get the following results for the base miss chance of a level 80 character attacking with a weapon that has 400 weapon skill:

Chance to dodge, parry, block and glancing blows

The exact chance that a boss has to dodge, parry or block any given attack isn't precisely known, and it is quite possible that the values actually vary form mob to mob. For all practical purposes, it has been determined that a majority of boss mobs have a 14% chance to parry attacks and 6.5% chance to dodge or block attacks. You can use Expertise Rating, not Hit Rating, to reduce a target's chance to parry or dodge attacks. Again, Hit Rating will have no effect on a target's ability to dodge, block or parry attacks.

Glancing blows have been a spot of contention from patch to patch for a very long time running. The last officially confirmed calculations for determining glance blows is this:

This was introduced back in patch 2.1. Using this model, a player would have a 25% chance to land a glancing blow against a raid boss. However, since patch 3.0, a vast majority of parses have placed the chance to land a glancing blow as being 24%. It is possible that the formula has been slightly changed since patch 2.1, but we cannot know for certain. When doing any form of theorycrafting, 24% chance of landing a glancing blow is the currently accepted figure.

When you land a glancing blow, it will deal 30% less damage than normal against a raid-level mob, with the damage reduction being reduced by 10% for every level closer to yours the target is. You can only land glancing blows against targets that are equal to or greater than your own level, and there is no way to reduce either the chance to land a glancing blow nor the damage penalty. Note that you cannot land a glancing blow against another player, only against NPCs.

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