OD&D Combat Modifiers Compendium

Knight charges dragon

There's a surprisingly small number of combat modifiers (adjustments to the combat rolls) in Original D&D. What did Gary and Dave think were important then? Using the 7th printing, let's take a look:

  Volume 1: Men & Magic

  • Fire missiles at +/−1 from Dexterity (p. 11)
  • Missiles decrease AC by 1 at medium, 2 at short range (p. 20)
  • Protection from evil spell gives "−1 from hit dice" (p. 23)
  • Bless spell gives +1 to atack dice (p. 32)

That's actually it! Pretty minimalist, isn't it?

Volume 2: Monsters & Treasure


  • Berserkers get +2 for ferocity (p. 6)
  • Dervishes get +1 like berserkers (p. 6)
  • Mermen, as berserkers, but −1 on land (p. 7)
  • Goblins, −1 in full daylight to attacks & morale (p. 7)
  • Kobolds, as goblins (p. 7)
  • Orcs, as goblins (p. 8)
  • Dragons, hit at +2 if sleeping; elemental attacks get +/−1 (p. 12)


  • Magic swords, adds +1 to +3 probability of hitting (p. 30)
  • Magic armor, subtracts 1 to 3 from hit dice of opponents (p. 31)
  • Magic miscellaneous weapons, as swords, +1 to +3 (p. 31)
  • Potion of invulnerability, +2 to defensive capabilities (p. 32)
  • Ring of protection, as +1 armor (p. 33)
  • Staff of striking, +1 to hit (p. 35)
  • Staff of wizardry, +1 to hit (p. 35)
  • Displacer cloak, +2 to defense (p. 36)

Vol-3: The Underworld & Wilderness Adventures

I actually couldn't find any combat modifiers in this volume.


Now, there's quite a bit of evidence that we are meant in include rules from Chainmail by reference, so as an added bonus here's a listing from the Man-to-Man Combat and Fantasy Supplement sections of that work. In fact, this may dig up most of the situational combat modifiers we would have expected from Vol-3. Looking at the 7th printing:

Man-to-Man Combat

  • Mounted vs. non-mounted: mounted get +1, non-mounted −1; or in first round horsemen add +2 (p. 25, repeated on p. 26)
  • Attacks against rear: add +1 to the die roll (p. 25)
  • Parry: subtract −2 from attacker's roll if allowed by weapon type (p. 25-26)
  • Leaders: +1 on all dice (p. 26)
  • Viking berserkers: +2 on attack dice (p. 26)

Note that inspecting the missile fire tables (p. 41), in the majority of cases, there is a +2 benefit to being at short range, and +1 for medium range.

Fantasy Supplement

  • Goblins/Kobolds: in full daylight or bright light subtract −1 from morale and any die rolled (p. 29)
  • Orcs: react to light as goblins (p. 30)
  • Heroes: add +1 to dice of their unit; +1 on dice for magic arrow vs. dragons; Rangers are heroes with +1 on attack dice (p. 30)
  • Elementals: add one or two to dice roll against favored opponents (p. 36)
  • Wights/Ghouls/Zombies: subtract −1 from die rolls in full light (p. 37)
  • Magical swords: +1 to dice score vs. fantastic creatures; super-swords like Excalibur may give +2 or +3 (p. 38)
  • Magic armor: subtracts −1 from opponent attacks on Fantasy Table, or −3 on Man-to-Man attacks (p. 38)


It's been said before, but one of the reasons I wanted these numbers collected in one place is this: While I didn't say it above, it's not entirely fair to compare all these numbers in parallel, because there's at least 3 different mechanical systems that might apply here.

  • For "normal" combat in the Chainmail Fantasy Supplement, 1d6 would be rolled per figure (using the same resolution tables as the mass combat base game).
  • For both "fantastic" and Man-to-Man Combat, 2d6 rolls are made as the mechanic.
  • For Original D&D "alternative" combat, the 1d20 is used. 

There's quite a bit of room for different interpretations about which system should be applied when. E.g.: The Chainmail Fantasy Supplement refers both to the regular mass combat tables, and also the Man-to-Man system (see under Magic Armor). The Original D&D text by default claims to use the Chainmail Fantasy system (but which one, when?), but has an "Alernative Combat" option using the d20 (and yet original players claim only the d20 system was ever used in practice). 

On the d6 the range is 6; for 2d6 the range is 11; and on the d20 the range is (obviously) 20. That is: the range of possible rolls roughly doubles in each step of these three systems. So if we were converting modifiers, we could reasonably expect to scale any one by about double for any level of transition. But this seems to have been overlooked, and modifiers are copied between systems unchanged. For example:

  • Berserker ferocity is +2 in both Chainmail and OD&D.
  • Goblinoid light penalty is −1 in both Chainmail and OD&D.
  • Magic swords and armor apply a +1 to +3 modifier in any book.
  • Missile-fire range adjustment of +1 or +2 is identical in each book.

Similarly, the situational modifiers we see in Chainmail Man-to-Man Combat (while not copied into OD&D) reappear basically unchanged in the 1E AD&D DMG. Note for one example the shift in the effect of goblinoid −1 penalty in daylight is enormously different from one extreme of systems to the other: in the OD&D d20 system, it's a fairly minimal 5% adjustment, whereas back in Chainmail Fantasy "normal" combat, it makes them utterly unable to hit anything except Light Foot (granted that all other targets are hit only on a "6" on d6).

Arguably, the most coherent interpretation might be that the OD&D text really was written assuming that Chainmail combat mechanics (well: some mix of the 3 there) were in effect, and the rise of the d20-based "Alternative" failed to take into account the need to adjust those modifiers. But no such errata ever appeared in either the supplements or even AD&D, so we got stuck with fairly fiddly small modifiers that at one point were huge game-changers.

Secondarily, there's also the interesting feature that some but not all monster modifiers got copied from Chainmail into OD&D. Things that were copied: bereserker ferocity and goblinoid light penalties. Things that were not copied: undead attack penalties in light (and also some things like special dragon senses, which reappeared in AD&D but not the B/X line).

Should we be adjusting modifiers that originally appeared in Chainmail (such as goblinoid light penalties) by as much as quadrupling them to scale to the d20 attack system? Anything that I missed in my survey?

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  1. I kind of feel that the modifiers ought to be adjusted when going from 1d6 or 2d6 to d20. A) it just seems wrong to me that the entire flavor of combat changes depending on whether you choose to use Chainmail as your combat system or the alternative d20 system. B) I hate fiddly bonuses like +1 or +2 where you can only discern the difference if you're tracking every blow. They're so easy to forget, and when you do it makes so little difference, so why are you trying to track them?

    That said, I think the evidence is pretty good that the game as has always been played by the majority of players had only those very minor bonuses when it comes to what Bless does or how badly goblins are penalized by light, so maybe that ought to count for something. And I certainly wouldn't want to double or quadruple the bonuses that stats give, especially when using the B/X style of -3 to +3 with mods for all attributes. I think that would feed into the "I have to have good stats or my character's useless!" that I find a problem with later editions.

    1. Totally agreed (as you can guess) on the situational modifiers like goblins in sunlight. I really do have a margin note to treat that as -4 in my OD&D book. On the obverse, I really don't want to spend mental energy on situational modifiers less than +/-2.

      But true, no way I would boost fixed ability modifiers beyond the 1-3 range. Fortunately, they don't exist in Chainmail so I think our hands are clean on that one.

  2. Interestingly, 5E D&D's Advantage/Disadvantage system works out to roughly +4/-4, which fits in nicely with the double-doubling of the essential +1/-1 bonus/penalty system. I doubt they took that into account when developing the system, but it certainly makes the modifier count!

  3. Quadrupling the +/-1 modifiers could make for some interesting tactics, but doing so to the larger modifiers might overwhelm the game. How unstoppable should a figure in magical plate be? How tough should it be to charge a group of archers?

    It reminds me of the combat tables from original Traveller, where you basically can't miss at short range with a shotgun. Very realistic, but hard to swallow when it happens to you!

  4. Warriors of Mars has something very similar to the Man-to-Man/Fantastic Combat system, but uses 3d6 and allows for wounding as well as killing outright (it also provides for scaring your foes, as well). Something worth looking at, if you get a chance.

    As an aside, were I just using the Holmes Basic or OD&D I would allow above/below average strength to adjust to hit chances in melee, analogous to the modifier for missiles for dexterity. Strength really does matter, and can sometimes make up for a lack of skill in "bulling" past your foe's defenses. Note that I dislike damage bonuses since [1] they can provide too great a modifier relative to the dice (i.e. a +1 on a d6 is a much greater adjustment than the same on a d20) and [2] it should always be possible to graze a foe with a "one point" hit, at least w.r.t. man sized "normal" opponents.

    1. I like your point about bonuses to damage, that's well-considered.

      Also agree that Warriors of Mars is an important document and many of us should read that. Of course, for me the most important thing is the very first thing: the explicit differences in scale given for mass vs. man-to-man combat (which is critically missing from Chainmail Man-to-Man rules and I hold corrupted the system from the start).

  5. Tough call. My suggestion is that you create a table of two columns. One column is just the raw modifiers as you list them above, and for the second column, list the adjusted values. DM's can then decide for themselves what to use. Oh, and great post as usual Delta.

  6. "Anything that I missed in my survey?"
    Are you considering race modifiers?
    The elves "gain the advantages noted in the CHAINMAIL rules when fighting certain fantastic creatures". One of these days I was converting these "bonuses" from the Fantasy table to the Alternative System, comparing to a Hero fighting the same monsters in both systems. I lost the spreadsheet where I was doing it, and now I'm to lazy to start over.

    1. Good question; the main thing is that I was restricting myself to stuff that explicitly added/subtracted pips to a die roll (i.e., the trad D&D idiom). Other modifiers that added extra dice (two Halflings firing count as three; Elves adding dice vs. goblins/orcs or with magic weapons) are much murkier to convert, like 5E Advantage, and I didn't touch those.

  7. Set spear against charge: "Additionally, if something impales itself upon the spear, damage will be double or even treble if the force is sufficient."(OD&D, Vol II, p. 31)

    Striking unarmored head: "any hit upon its wearer should be given a 10% of striking the [magical, non-armored] helm and smashing it." (Vol II, p. 37)

    Hand held missiles: "[the axe] can be utilized as a hand weapon or thrown 3” with the +1 bonus. Treat all targets as at medium range, i.e. there is neither short nor long range for this weapon." (Vol II, p. 31)

  8. I've wondered about this exact discrepancy. Goblins, orcs, and kobolds at serious disadvantage in daylight and berserkers being truly scary sounds so much more flavorful. Porting to my game. Nice post!

    1. Hey, I'm glad! Definitely like it in my game.

  9. So tempted to try a 2d6 <= AC combat system with these modifiers!

  10. The rare times I dip into the old books I keep it simple and cherry pick very select things to use. The whole point for me is super simple D&D. But the supplements are used of course.

  11. "Missiles decrease AC by 1 at medium, 2 at short range (p. 20) "

    Holy Hanna, how the hell did I miss that? That makes missile weapons really frakkin' scary! I might have to try that out.

    1. I feel like I may have written something about missiles in D&D being insanely hyper-accurate, let me see if I can find that somewhere... :-)