So every once in a while I see a proposal for called shot rules in D&D
("called shot" meaning a deliberate attack against a specific part of the
body, such as a head shot for an instant kill, cut off a hand, groin kick,
etc.). Personally, I feel that's a bad idea.
The D&D combat system assumes that your armor and shield protect your
entire body equally. This is for simplicity's sake and because much in D&D
combat is an abstraction for the sake of making combat proceed at a reasonable
You'll notice, for example, that you can't get "behind" a person to attack
them without their shield bonus ... there's no "behind" someone in D&D
because there's no definite facing (i.e., a character isn't assumed to be
facing in a particular direction at a particular time). D&D approximates
being able to get 'behind" someone with the flanking rules, but that requires
another person to flank the target (because a combat round is six seconds,
if you are aware of someone you have plenty of time to react to their attack,
assuming you're not flat-footed). Likewise, when attacking someone who is
unarmored except for a shield, you can't aim for parts of the body that aren't
covered by the shield; its armor class bonus applies to the character's entire
If you allow characters to make called shots, it defeats the purpose of wearing armor. Here's an example scenario.
Bronn the Blackguard is completely armored in full
plate. Because he has no Dex, deflection, or other bonuses to AC, that makes
him AC 18. Bronn has an open-faced helmet. His arch-foe, Freya the Fighter,
has a crafty player who wants to try to make an attack against the Bronn's
unarmored face, which theoretically is AC 10 (just like a fully unarmored
character). You could rule that the unarmored face counts as a Fine creature,
and thus has a +8 size bonus to AC, making the face AC 18. Now maybe 1/10
of him is AC 18 (10 +8 size), and the other 9/10 is AC 18 (10 +8 armor).
So if Freya attacks Bronn's face, she has the same chance to hit the armored
body or the unarmored face. If she aims for the face and hits, you have two
1. Let the hit do more damage against the unarmored face than it would against the armored body (or armored face/head). One problem with that: if hitting an unarmored face does more damage than hitting a helmed face, then any hit against an unarmored character should do more damage than a hit against an armored character; suddenly you have to recalculate damage values against unarmored creatures, and armorless characters (such as mages and most monsters) suddenly are even more vulnerable. "More damage" also includes special effects that most people associate with critical hits: blindness, stunning, crippling, tripping, instant kills, etc.
2. Have it do normal damage, just like hitting an armored part. But that means that the character has gained nothing for trying to hit a vulnerable spot. If you're going to include rules for called shots and not reward players for using those rules, why have those rules at all?
I admit, the "attack the face" scenario is the most extreme example, but
the point still applies for larger unarmored parts of the body. Another example:
Bronn the Blackguard wears the upper half of a suit of full plate,
and his legs are unarmored. The game effect of this is that he's protected
just like wearing breastplate (AC +5) and moves as if he's wearing breastplate
(Why would he do this? Who knows, maybe this is the only piece of a famous
blackguard's armor that was salvaged from an acid pool, and he bought it
for breastplate price from an evil temple because he wanted to wear this
famous piece of armor.) So his upper half is AC 15, his lower half is AC
10. If Freya the Fighter wants to attack his unarmored legs, you could rule
that she's attacking a Small target (+1 size bonus to AC), so attacking his
legs requires a roll against AC 11. Here's the weird thing: if she has the
Sunder feat and decides she wants to wreck that legendary armor (ignoring
that the rules don't address how PCs can attack armor as opposed to weapons
or shields) and specifically attacks his armored parts, his upper half gets
a +1 size bonus to AC ... so it's actually harder to hit him specifically
in his armored parts than it is to hit him without care for where the blow
lands! Anyway, if she his his unarmored legs, we have two options:
1. This is the same option 1 in the previous example ... you have to figure different damage against unarmored parts.
2. Have it do normal damage. This is like option 2 in the previous example, but now the chances to hit his unarmored parts are much better than the previous scenario. Now 1/2 of him is AC 15 (10 +5 armor) and 1/2 is AC 11; he spent 200 gp on this armor and half the time it's no better than 5 gp padded armor! Suddenly the game effects of armor are much weaker, and characters that rely on armor are weakened because of it.
The "half a suit of full plate" example is completey arbitrary because
very rarely does a suit of armor have entire pieces missing. But remember
that every piece of armor has strong parts and weak parts—joints have to
be flexible to allow movement and therefore are more vulnerable, and so on. So you could
say that most of a suit of full plate grants +8 to AC, but there are parts
that only grant +6 to AC or even +4 to AC; you could come up with a "map"
for each armor giving the relative armor and size bonuses for each body part,
allowing characters to attack weaker points in the armor. So the "half a
suit of full plate" example is simply a black-and-white example of the shades-of-gray
problem with called shots.
Creating such a map adds an extra element of time to every combat. D&D
combat assumes certain things to speed up gameplay (a real-world hour of
combat where everyone gets to act six times is more fun than that same hour
where everyone only gets to act once). When you increase the amount of realism
in the rules, you increase the complexity ... quite often complexity that
was deliberately taken out of the game to make it run faster.
Fortunately, D&D does have a system for handling especially
well-placed hits against enemies: the critical hit. The game even has a system
for characters to learn how to place such blows more often: the Improved Critical
feat. So there's already stuff built into the game to handle the effects
of called shots without having to introduce the complexity or the problems
of actually requiring specific called shots. Trying to build more complex
stuff into the game introduces some problems, slows down gameplay, and either
makes armor even more valuable than it already is (by dealing more damage
to armorless characters as compared to armored characters) or makes armor
much weaker than it should be (by allowing attackers to easily bypass armor's