Some weapons, like Morningstars and Sugliin, do two types of damage at once (Piercing/Bludgeoning and Piercing/Slashing, respectively). How does this interact with underwater combat penalties? Normally a weapon that does piercing damage isn't subject to such penalties, but slashing and bludgeoning weapons take damage penalties underwater. Which way do these dual-type weapons swing?


1 Answer 1


So the “primary source” for this rule is the Dungeon Master’s Guide. Unfortunately, its implementation of this rule is just a table, with no accompanying description:

Land-based creatures can have considerable difficulty when fighting in water. Water affects a creature’s Armor Class, attack rolls, damage, and movement. In some cases a creature’s opponents may get a bonus on attacks. The effects are summarized in the accompanying table. They apply whenever a character is swimming, walking in chestdeep water, or walking along the bottom.

(Dungeon Master’s Guide, pg. 93)

Table 3–22: Combat Adjustments Underwater

Condition Slashing or Bludgeoning
Movement Off Balance?⁴
Freedom of movement normal/normal normal/normal normal No
Has a swim speed −2/half normal normal No
Successful Swim check −2/half¹ −2/half quarter or half² No
Firm footing³ −2/half −2/half half No
None of the above −2/half −2/half normal Yes
  1. A creature without a freedom of movement effects or a swim speed makes grapple checks underwater at a –2 penalty, but deals damage normally when grappling.
  2. A successful Swim check lets a creature move one-quarter its speed as a move action or one-half its speed as a full-round action.
  3. Creatures have firm footing when walking along the bottom, braced against a ship’s hull, or the like. A creature can only walk along the bottom if it wears or carries enough gear to weigh itself down—at least 16 pounds for Medium creatures, twice that for each size category larger than Medium, and half that for each size category smaller than Medium.
  4. Creatures flailing about in the water (usually because they failed their Swim checks) have a hard time fighting effectively. An off-balance creature loses its Dexterity bonus to Armor Class, and opponents gain a +2 bonus on attacks against it.

(Dungeon Master’s Guide, pg. 92)

That’s it: look at the table, it’s got “Slashing or Bludgeoning” on it.

Worse, Rules Compendium repeats these rules... mostly. It doesn’t include the table, and instead spells out the same information in text. Well, mostly the same—there’s one crucial difference:

Creatures with no swim speed

Certain penalties apply whenever a creature that doesn’t have a natural swim speed is swimming. These penalties also apply when a creature has firm footing but is largely beneath the surface of a liquid, such as when walking in chest-deep water, or walking along the bottom of a pool. Such a creature takes a –2 penalty on attack rolls and deals half damage, unless it’s using a piercing melee weapon or a natural weapon that strikes as a piercing weapon. The creature also makes grapple checks underwater at a –2 penalty, but deals damage normally when grappling. A freedom of movement effect allows a creature to ignore these penalties.

Creatures with a swim speed

Creatures that have a natural swim speed aren’t subject to the penalties for fighting underwater when grappling or using constrict attacks, piercing attacks (including a bite), rake attacks, ram attacks, rend attacks, tail attacks, or tentacle attacks. Slam attacks that represent full-body rams, such as a porpoise’s slam attack, don’t take the penalties. An elemental of the water subtype can use any of its natural attacks without penalty while underwater.

Since a creature that has a natural swim speed doesn’t need to make Swim checks to move around, it’s never considered to be off balance.

(Rules Compendium, pg. 149, emphasis mine)

So Dungeon Master’s Guide says that “Slashing or Bludgeoning” takes penalties, and Rules Compendium says that weapons take the penalties “unless it’s […] a piercing melee weapon.”

This is a problem because the weapons you’re talking about are in both categories. This, at least, the rules make very clear:

Some weapons deal damage of multiple types. If a weapon is of two types, the damage it deals is not half one type and half another; all of it is both types. Therefore, a creature would have to be immune to both types of damage to ignore any of the damage from such a weapon.

(Player’s Handbook, pg. 114)

(Though the very next paragraph describes other weapons that can do one or the other at the wielder’s option, which are back to being somewhat unclear—does a weapon that can do one type of damage count as a weapon of that type when it’s not being used that way? Community consensus here is “No,” but the rules text isn’t exactly explicit about it.)

Anyway, faced with this contradiction, it’s pretty much up to the table/DM. You could get into arguments about whether or not Rules Compendium supersedes the core rules, but there’s not much point—regardless of which you go with, it doesn’t seem very likely that the authors of either book actually considered these weapons in this situation, so at that point you’re picking a source and trying to extract information that the authors never (intentionally) put into it.

Officially, that’s the end of the story: this is a core rule and the core rules don’t have a clear answer. Even if something else somewhere else has an answer, it wouldn’t count, technically.

But it still might be interesting and useful to know that something does. As @Peregrin helpfully points out in a comment, Stormwrack’s Toothed Blow feat assumes a bludgeoning-and-piercing weapon avoids underwater penalties. That is decent circumstantial evidence that it’s supposed to. It could just be wrong, but since it is the only thing that seems to address the question specifically, you might decide it is the best basis available to make a ruling.

Ultimately, the penalties for fighting underwater are immense without freedom of movement. This tends not to come up because characters tend not to even bother to try it; they try to get out of the water, instead. (Creatures who are meant to live and fight underwater take far fewer penalties.) Even the authors themselves don’t seem to like their own rules: Rules Compendium spends 20% of the page on underwater combat on a sidebar discussing one author’s houserules eliminating most of them.

If you’re inclined to keep them, though, I would suggest that at least being lenient about what weapons you can use underwater would help matters. I would allow a morningstar or sugliin to be used without penalty underwater. Nonsense, but it’s good for the gameplay.

  • 2
    \$\begingroup\$ Stormwrack has a feat called Toothed Blow with the benefit: When making unarmed strikes, your attacks count as piercing weapons as well as bludgeoning weapons. This allows you to avoid the penalties for using bludgeoning weapons underwater when making unarmed strikes – The wording of this feat seems to support that piercing-dual-damage-type weapons suffer no penalties underwater... \$\endgroup\$
    – Peregrin
    Dec 7, 2023 at 16:13
  • \$\begingroup\$ @Peregrin True! Unfortunately, Toothed Blow could just be wrong about that—a feat isn’t allowed to define core rules, and if it includes a definition for anything, that is officially regarded as only a reminder and official guidance is to ignore it if it contradicts the primary rule. So if the core rules disagree, Toothed Blow is just wrong. We don’t know if the core rules disagree, but agreement with Toothed Blow is a circumstantial consideration at best. \$\endgroup\$
    – KRyan
    Dec 7, 2023 at 16:54
  • \$\begingroup\$ @Peregrin Excellent find! I had completely forgotten about that feat. That's all the evidence I need to convince me it is at least RAI and probably RAW that dual-type damage weapons ignore the penalties. \$\endgroup\$
    – Elliot
    Dec 7, 2023 at 16:54
  • \$\begingroup\$ @Elliot Definitely not RAW, since the errata rules make it clear that, RAW, Stormwrack (much less a single feat therein) doesn’t get to make that call. As for RAI, the intent of Toothed Blow’s author is clear, but we can’t assume they were necessarily on the same page as other authors here. Editors are supposed to make sure they are, but... they often did not. \$\endgroup\$
    – KRyan
    Dec 7, 2023 at 17:10
  • \$\begingroup\$ @KRyan Yes that was badly phrased on my part. What I mean is that "being a piercing weapon means you don't suffer penalties" is a valid reading of the Rules Compendium line, made ambiguous by the existence of the table, but Toothed Blow gives a clear example of it being interpreted in that way. In lieu of a counterexample, I can't see many GMs overruling that interpretation. \$\endgroup\$
    – Elliot
    Dec 7, 2023 at 19:20

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