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Many monsters have very dangerous natural attacks (like scorpion's poisonous sting, for example). Sometimes players come to a decision to severe the natural weapon first and then deal with a much less dangerous opponent. An obvious choice for that is sunder special attack. But PHB and DMG lack some vital statistics for that.

  1. There are no explicit rule for determining natural weapon hardness and hit points.
  2. It is strange to assume that severing body part deals no damage to the monster itself, but it is unclear how much damage to monster total HP such an attack would deal.

I've been comparing a natural weapon to an artificial weapon and assigning the same hardness and HP to it. And using rules for severing hydra heads for damage dealt to the monster total HP (half damage dealt to the natural weapon).

But I wonder if there are any explicit rules for sundering natural weapons in any 3.5 source.

The in-game problem to solve is: what should I, as a DM, answer to a player who declares "I'm trying to hit scorpion's sting with my sword"? While the sunder mechanics seems the most apropriate to me, I would accept any good solution. Rules from the books are preferred, but play tested house rules are also welcome.

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  • \$\begingroup\$ @KorvinStarmast I'm not shure I understand your question clearly. I'm trying to render natural weapon useless through a sunder attack. It has nothing to do with critical hits as far as I can see. \$\endgroup\$ – Ols Sep 1 '16 at 12:54
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    \$\begingroup\$ @KorvinStarmast In fact, the question is: what should I, as a DM, answer to a player who declares "I'm trying to hit scorpion's sting with my sword"? The sunder mechanics seems the most apropriate to me, though I would accept any solution. Books are prefered but play tested houserules are also welcomed. \$\endgroup\$ – Ols Sep 1 '16 at 13:24
  • \$\begingroup\$ @KorvinStarmast Thanks. This edit makes the question better, I think. \$\endgroup\$ – Ols Sep 1 '16 at 13:49
  • \$\begingroup\$ Highly related: rpg.stackexchange.com/questions/75781/… \$\endgroup\$ – Jeffrey Bosboom Sep 2 '16 at 6:17
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No, there are no such rules for sunder in particular

Excepting special cases for particular monsters, as with hydras or krakens.

The rules for sunder explicitly begin with

Sunder

You can use a melee attack with a slashing or bludgeoning weapon to strike a weapon or shield that your opponent is holding.

(emphasis mine)

There is an additional section for a carrier or worn object, but that still doesn’t apply to natural weapons.

In online discussions of sunder, the inability to use it on natural-weapon-using monsters is frequently brought up as a massive problem with the tactic (though far from the only one). I have never seen anyone mention any official rule for sundering them, nor have I ever seen such a rule myself, strongly supporting my broader claim that no such rule was published in a supplement. I specifically checked Rules Compendium, as the most likely location of such a thing, and it only reprints what core had to say (plus a little sidebar on how a DM should prepare encounters when a PC is using sunder).

As for houserule, I have not used, or seen used, any particular rules. Most seem willing to accept that sundering is just a dead rule, that is undesirable for PCs and (often) obnoxious and unfun for use by NPCs. There have been few, if any, attempts to rehabilitate it, and I’m not familiar with any. Your approach of using the hydra’s rules seems appropriate, though I wouldn’t guess that bone and hide, even fantastic bone and hide, has the same Hardness as steel.

There may be optional, variant rules for called shots, but....

I have to admit that I am not familiar with any official variant rules for called shots, but I suspect they exist (and homebrew versions certainly exist as well). However, I would caution against them: they are, in effect, like super-charged criticals. Many even run off of critical mechanics, but even when they don’t, by definition you are talking about something with a lower chance of a higher consequence.

The problem with this is that it degrades the stability of the system. The ability to predict consequences and prepare for them is diminished, and the game was already quite swingy. I would argue, then, that these effects are to the detriment of the game.

You may disagree; you might want something even swingier. That’s fine, as long as you have a group that’s on board with that, but I think it is important that you and your group all know the ramifications here: swinginess is inherently bad for the players. Mathematically, a dire consequence as a result is equally likely for PCs and NPCs (assuming they’re making similar numbers of attempts, which seems mostly reasonable), but while such bad luck against NPCs is much more likely than not to befall some random mook, the same bad luck against PCs will land on a PC 100% of the time by definition. And since there are relatively low risks of these consequences, it is more difficult to defend against them—player resources are already devoted to a number of things they need to defend against as it is, so it will be difficult to justify diverting some of them to protect against a low-risk event.

Called shots are far better than critical or fumble tables in that they are specific, planned maneuvers, so they avoid a lot of the huge narrative failings of critical or fumble tables. So that much is good. And since you are presumably giving up an attack or something else to attempt these called shots, your odds can be reasonable, and if the odds are reasonable, the effects need not be so dire. So a well-made system could mitigate some of the mathematical problems I mention above. But it is important that, whatever you choose, you go into it with eyes open, aware of potential problems. Unlike critical or fumble tables, they’re not insurmountable for a group that’s interested in this sort of thing, but they’re not something to add on a whim because it sounds cool. Consider it carefully.

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  • \$\begingroup\$ @KorvinStarmast Personally, I find called-shot rules inappropriate and nonfunctional in d20, and ignore them where they exist. I probably have seen variant rules or whatever for them, but I’m sure they aren’t good and I don’t know exactly where to find them. Dungeon Master’s Guide and Unearthed Arcana are decent bets, though. \$\endgroup\$ – KRyan Sep 1 '16 at 13:15
  • \$\begingroup\$ Heh, while I personally disagree that swinginess is inherently bad for the players in the context of this answer it fits beautifully into laying the foundation for a DM approach to his problem. As I've already upvoted the answer, I can't up vote it again(Darn it). \$\endgroup\$ – KorvinStarmast Sep 1 '16 at 15:25
  • \$\begingroup\$ @KorvinStarmast I mean, this is pure mathematics. The PCs by definition have to be in it for the long haul. That means they need to have things as stable and consistent as possible (and consistently come out on top). Swinginess is the opposite of that. Mathematically, odds are much, much better that a bad swing is going to take out a PC than that they are going to take out a major enemy, because the PCs fight a lot of minor enemies who can get lucky, and the major enemies don’t. \$\endgroup\$ – KRyan Sep 1 '16 at 16:03
  • \$\begingroup\$ I understand that, but a DM isn't a pure math engine. The DM doesn't have to always apply that kind of attack, and most players use weapons, not "natural attacks" (though a druid in animal shape might be very vulnerable to the numbers closing in, as you point out, from plentitude of die rolls). And how "swingy" each table likes its play is variable. Your core point on why the PC's get overexposed to that risk is not disagreed, since as you say the odds will eventually converge. \$\endgroup\$ – KorvinStarmast Sep 1 '16 at 16:05
  • \$\begingroup\$ @KorvinStarmast The statement was that swinginess is bad for PCs. Your counter is that the DM doesn’t have to make it as swingy as he might—which I absolutely agree with, mention in the answer, and suggest that he does what he can because swinginess has inherent mathetmatical problems for PCs (which cause problems for the functioning of the game) even if the group is on board. And of course, there is considerable latitude for preference in that. The purpose of the answer is purely to provide information so choices about these things can be made aware of potential pitfalls. \$\endgroup\$ – KRyan Sep 1 '16 at 16:08
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Effects Refer To Limb Loss, With No Mechanic

There are many references scattered throughout the rules to creatures regrowing severed limbs and severed body parts reverting to their original form. Yet there are almost no rules covering how it could happen in the first place.

There are no 'called shot' rules within Official D&D 3.5 rules, and the damage rules are intentionally abstracted. The closest are the Variant Rules for Damage to Specific Areas on p27 of the 3.5 DMG.

Making the game 'grittier' by making limb-loss and death by beheading possible is not necessarily a good thing, but called shots as optional rules existed in AD&D 2e definitely, and it had the Sword of Sharpness, for example; on high rolls it severed parts.


Untested House Rule: Extrapolate From the Hydra, Giant Squid and Kraken Rules

The hydra's combat rules are fairly complete as to how sunder works against them:

To sever a head, an opponent must make a successful sunder attempt with a slashing weapon.

This is not unreasonable, in fact it's pretty good, but ruining a limb might be reasonably accomplished with a bludgeoning weapon, and the sundering rules for objects, which both kraken and squid reference unchanged, supports this. The limitation to slashing is likely a holdover from 3rd ed., where sunder required slashing only (PHB 3.0, p136, 'Strike a Weapon'). This DM doesn't see piercing weapons as reasonably disabling limbs.

(The player should declare where the attack is aimed before making the attack roll.) Making a sunder attempt provokes an attack of opportunity unless the foe has the Improved Sunder feat.

This is the 'cost' of the 'called shot' option; take an AoO or take a feat. The would-be sunderer still has to succeed an opposed attack roll, modified by creature size and weapon size. Natural attacks are usually 'light' weapons, but this DM would rule that for this check they're 'one-handed', and heads are '2-handed', just to keep things cleaner.

An opponent can strike at a hydra’s heads from any position in which he could strike at the hydra itself, because the hydra’s head writhe and whip about in combat.

This is a holdover from the facing rules of 3rd edition, and barring Unearthed Arcana options, can be ignored; you can attack any part of a creature, and it can attack in any direction in D&D 3.5.

An opponent can ready an action to attempt to sunder a hydra’s head when the creature bites at him.

You can do this with sunder versus a held weapon as well.

  • Each of a hydra’s heads has hit points equal to the creature’s full normal hit point total, divided by its original number of heads.
  • kraken’s tentacles have 20 hit points, and its arms have 10 hit points.
  • giant squid’s tentacles have 10 hit points each.

This is the part that differs with the rules-legal sunderable natural weapons or heads; the HP calculation.

This DM would probably rule that the Hydra's head-HP rule should be the basis for all heads; full normal HP divided by original number of heads.

not recommended

Alternatively, rather than the explicit rule, you could extrapolate that since hydras have 1 HD/head, then each creature's head has 1 Racial Hit Die plus Con modifier per head. Therefore fey have weaker necks (1d4+con) than undead (only vampires, mostly) (1d12) or dragons (1d12+con). The benefit, if it could be said to be, is that it's a static number; humanoids will always have 3.5+con HP per head. It makes Vorpal weapons hugely overpriced; just get sundering (MIC p.44) as a +1 add-on.

Limbs are more difficult to adjudicate, but allowing only the sundering of natural weapons, other than bite (heads) rather than limbs simplifies things. If that is done, primary weapons would have HP as light weapons of the creature's size, and secondary weapons would have HP as light weapons of one size below the creature's size. This appears to be how the kraken and squid tentacles and arms are priced.

Thus:

Fine-Tiny: [Weapons either too small to target, or treat as 1 hp ea.]
Sml: Pro, 1 hp; Sec, [untargetable, or 1 hp]
Med: Pri, 2.5 hp; Sec, 1 hp
Lrg: Pri, 5 hp; Sec, 2.5 hp
Hug: Pri, 10 hp; Sec, 5 hp
Grg: Pri, 20 hp; Sec, 10 hp
Col: Pri, 30 hp; Sec, 20 hp

Weapons that would have less than 1 hp are either too small to sunder, or they merely have 1hp minimum, DM's choice.

Losing [an attack or head] deals damage to the body equal to half the [part’s] full normal hit points. [Losing all of its heads kills living creatures that have heads]

This is good as-is, for the most part.


The Game Would Change

Intelligent creatures, as well as many unintelligent predators, would use this method in melee, especially if the lower value for head HP were in use. It's effectively what feline predators try to do in real life; sever the spinal cord near the prey's head.

Living creatures with heads, and all creatures with natural attacks would become more vulnerable, but allowing melee attackers to 'disarm' (Ow, the pun! It's excruciating!) creatures' natural attacks gives non-spellcasters 'save-or-die' and 'debuff' options without long feat chains.

That's verisimilitude, sorta.

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  • \$\begingroup\$ @KorvinStarmast Thanks; I didn't think to remove the reference until just now, though ... \$\endgroup\$ – Chemus Sep 6 '16 at 17:31

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