Monthly Archives: June 2011

Chainmail And Weapon Modifiers

In my last post I took a look at the Chainmail Man-to-Man tables and distilled each armor class down to a standard to-hit value. To spare you the pain of looking back over that rambling mess, here’s the table of to-hit values for every armor class, listed for 2d6 and d20 combat, as well as a straight percentage chance of hitting.

9

8

7

6

5

4

3

2

2d6

7

7

8

8

9

9

10

11

d20

10

11

13

13

14

15

18

19

d100

0.57

0.5

0.42

0.42

0.35

0.29

0.15

0.1

Recall that, in Chainmail, AC 9 represents an unarmored opponent, AC 8 represents leather armor, AC 7 a shield alone, AC 6 leather and shield, AC 5 chain mail, AC 4 chain and shield, AC 3 plate armor, and AC 2 plate and shield.

This table shouldn’t be too big of a shock. It follows more or less the progression suggested in the “Alternative Combat System” in Original D&D, with the caveat that plate is significantly better than chain mail. Now we’re going to move on to weapon modifiers. In Chainmail, every weapon has a certain chance to hit each armor class. In this distilled system, this is represented by a table of to-hit modifiers, where the weapon is compared against the armor class, and a certain bonus added to the to-hit roll. Below is the table used when the 2d6 combat system is used.

Reach

9

8

7

6

5

4

3

2

Dagger

1

1

0

0

0

0

-1

-2

-1

Hand Axe

1

0

0

0

-1

-1

-1

-1

-1

Mace

3

-1

-1

0

-1

1

1

3

3

Sword

4

0

-1

0

-1

1

0

0

0

Battle Axe

5

-1

-1

0

0

2

2

1

1

Morning Star

6

1

1

1

1

3

2

2

3

Flail

7

0

0

1

1

3

2

4

4

Spear

8

-1

-1

-1

-1

-1

-1

-1

-1

Polearm

9

1

1

2

1

1

1

1

1

Halbard

9

-1

-1

0

1

3

3

3

3

Two-Handed Sword

10

1

1

2

2

4

4

4

4

Mounted Lance

11

2

2

3

3

2

2

2

2

Pike

12

-1

-1

0

0

1

1

1

1

Any positive numbers are simple bonuses to be applied to the to-hit rolls, while negative numbers are penalties. Using this table, we get exactly the same combat odds as in the original Chainmail. It’s obvious from the above table that some weapons, especially bigger ones such as the two-handed sword and the mounted lance, are simply better than their counterparts. To get a feel for exactly how much bigger, in a language that D&D players are more likely to understand, here is the same table converted to the d20 system (following the to-hit numbers stated earlier in this post).

Reach

9

8

7

6

5

4

3

2

Dagger

1

3

2

0

0

-1

-3

-2

-1

Hand Axe

1

0

2

0

-3

-4

-3

-1

-1

Mace

3

-3

-2

0

-3

1

2

9

6

Sword

4

0

-2

0

-3

1

0

0

-1

Battle Axe

5

-3

-2

0

0

5

6

2

1

Morning Star

6

3

4

3

3

7

6

5

6

Flail

7

0

2

3

3

7

6

11

10

Spear

8

-3

-2

-2

-3

-4

-3

-1

-1

Polearm

9

3

4

6

3

5

2

2

1

Halbard

9

-3

-2

0

3

7

9

9

6

Two-Handed Sword

10

3

4

6

6

10

11

11

10

Mounted Lance

11

5

6

8

8

7

6

5

4

Pike

12

-3

-2

0

0

1

2

2

1

Now it should be a lot clearer exactly how much better than your standard weapons the two-handed sword, for example, is. To penetrate plate and shield a standard character with a two-handed sword needs to roll a 9 or higher on a d20.

You’ll notice also that weapons have a “reach” value (this is called “class” in Chainmail, but I think “reach” is more descriptive). This has the following effects:

  • In the first round of melee between two opponents, the attacker (being the one who moved into melee) strikes first unless the defender has a weapon whose reach is 2 greater than the attacker’s. This simulates the defender setting his spear or whatever against the charge.
  • In the second and each subsequent round of melee, the same person who struck first last round does so again, unless the opponent has a weapon whose reach is 2 lower than the first combatant’s. This simulates the added speed and maneuverability that having a lighter weapon gives you.
  • If combatant A’s weapon has a reach of anywhere from 3 lower than combatant B’s to 1 higher than combatant B’s, combatant A can parry his opponent’s attack, forcing him to subtract 2 from his to-hit roll, though combatant A can not make his next attack.
  • If combatant A’s weapon has a reach from 4 to 7 lower than combatant B, then combatant A can either choose to strike first or parry combatant B’s blow. If the parry is successful, combatant A still gets to make his counterattack.
  • If combatant A’s weapon has a reach of 8 lower than combatant B, then combatant A gets the first blow, plus he has the option of striking again or parrying.
  • Any combatant whose weapon’s reach is at least 4 lower than his opponent’s gets another blow in addition to the benefits listed above.

So now we have different weapons that feel completely different, so while a burly fighter wielding a two-handed sword might make mincemeat out of a scrawny magic-user with his dagger, the magic-user still gets two chances to strike the fighter before the fighter even makes his first attack roll. Under the Chainmail rules, weapons are all different, many weapons having certain advantages over others. We’ve given weapons character even though they all deal 1d6 damage with a successful hit.

This also goes a long way towards differentiating classes at lower levels. I’ve often heard the complaint that, at low levels, there is no difference in fighting capability between fighters, clerics, and magic-users. Now the difference is clear: fighters can use any and all weapons, from the lowly dagger to the mighty two-handed sword, while magic-users can only use a knife. Not only would these two classes have different results in combat, playing them would feel very different.

Now what of when PCs are fighting monstrous creatures that have no immediate analogue in the weapon vs. AC table? I think the best solution is to give each weapon a simple modifier to hit to be used when facing monstrous foes. This modifier would be used regardless of the opponent’s armor class, and would simply be a reflection of the overall effectiveness of a weapon. Or you could just leave that system the way it is, and give those magic-users a fighting chance against a dragon.

You may notice I haven’t covered ranged weapons. This is because ranged weapons suck, and the math involved sucks, and I haven’t had the drive or opportunity to do it yet. I also haven’t talked about combat progression yet. I’ll get to that as well, but again the math is a bit wonky, or at least it seems that way to me. As it is this post pretty much outlines an entire combat system that you can plop into a D&D game. I plan on using this in my next game, whenever that happens, either in a 2d6 or a d20 form.

Whew. That was a lot of post with very little fluff. Here are some pictures to make everybody chill.

My latest D&D-related acquisition.

My current sci-fi reading.

Lumpy Space Princess

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This Is Chainmail. This is D&D.

[WARNING: This post contains nerdery and numbers. Proceed at your own risk.]

About a year ago I wrote this analysis of the Chainmail mass combat rules. I have this on-again off-again project I’m working on, which basically amounts to a retroclone. Basically I’m looking to write a system that stays very true to the original rules as written, with cool things added on from later iterations of the game in a way that they don’t upset the original spirit. Yes, this is more or less a set of house rules, that I at one point tend to write up in some sort of organized book-like file, more for my own gratification and the people I game with than for public consumption.

This is pretty long and rambly, so here's a picture of what Google assures me is Harold's death as presented in the Bayeux Tapestry.

One of my primary concerns in the crafting of this system is adhering to the rules as presented in Chainmail since the original rules for Dungeons & Dragons mentioned explicitly many times that the rules were to be used in conjunction with Chainmail. For those unfamiliar with that game, there are basically three different levels of combat detailed in Chainmail. The “standard” game is played between armies with figures representing twenty men apiece. The “Man-to-Man” rules deal with skirmish-level combat, where each model is an individual combatant. Fantasy combat deals with contests between fantastic creatures, such as dragons and trolls and the like.

In the post I referenced a year ago, I dealt with the standard 20:1 rules. That post was more-or-less a distillation of the base system, but my thinking at the time was to use that, along with the “Fighting Capacity” designations for each class as detailed in the LBBs, to fight smaller-scale conflicts. I dedicated a great deal of time and effort into making a combat system that would closely follow the guidelines laid down in that post. However, in so doing, I gradually came to the realization that, for the typical combats that my players tend to get into, those rules are just not fun, and any alteration I made to them took them farther from the spirit of the original. I often found myself stuck between that which is true to Chainmail and that which is fun.

So I’m abandoning that train of thought for the time being to focus more on the Man-to-Man rules. Looking at these, it’s much closer to the standard D&D combat with which we’re all familiar. In fact, one could easily just pick up the rules wholesale and drop them into D&D and have a perfectly workable system. So why not just do that? There are two problems.

  • The rules assume all combatants are of equal skill, with the only difference being equipment. Keeping this standard would basically make leveling up a simple matter of better saves and better hit points for the fighter, with no improvement in fighting capability whatsoever.
  • All attacks are rolled on a table, where the attacker’s weapon is cross-referenced with the armor of the defender. This is wonderful for two humanoids in battle, but it is completely unworkable for creatures like dragons, or creatures wielding exotic gear, or bears.

OK, so that first problem can probably just be fixed by giving higher-level fighters some sort of bonus to their die rolls or whatever. I’m not dealing with it at the moment.

The second is more problematic, seeing as how the game is Dungeons & Dragons, and a combat system that doesn’t let you fight dragons doesn’t really gel. So how do we deal with it? One option is simply to assign those monsters the armor that most closely approximates their natural defenses. A troll, with its thick, rubbery hide, might be given a leather armor class, whereas a scaly dragon would get plate. I imagine most animals would be assigned leather or no armor under this system, and we can tack on additional rules, such as small creatures forcing the attacker to subtract 1 from his to-hit roll.

That might be one way to go, but then what happens when those creatures attack? Do we likewise assign them a weapon? What would a dragon’s bite be? The system as written has the effectiveness of certain weapons versus certain armor deeply entrenched, and it seems like trying to shoehorn a bunch of non-humanoids into the mix takes away from the original intent.

The alternative that I propose is to assume that the system as it stands represents not only a weapon’s inherent usefulness against a certain armor type, but a combatant’s knowledge of how exactly to use such weapon to its greatest advantage (and perhaps the defender’s ability to counter those weapons which are easily countered). If we give each armor type an armor class (say, between 9 and 2), we can give each armor class a certain percentage chance to hit, which is used universally. If the combat is between two humanoids, we then have a separate set of modifiers for each weapon against different types of armor. When humanoids fight fantastic creatures, there are no modifiers, representative of the fact that the combat tactics to fight, say, a dragon, are quite exotic to the warrior, so he can’t make use of any inherent advantages his weapon may have over the opponent. If this seems familiar, it’s because it is basically the system used in 1st edition AD&D.

To find the baseline probability to-hit for each armor class, I took the average of every weapon’s ability to hit every armor class, percentage-wise. The results are as follows:

Unarmored (AC 9): 57%
Leather (AC 8): 50%
Shield (AC 7): 42%
Leather & Shield (AC 6): 42%
Chainmail (AC 5): 35%
Chain & Shield (AC 4): 30%
Platemail (AC 3): 15%
Plate & Shield (AC 2): 10%

You’ll note that in the original rules wielding a shield alone is on average better than wearing leather armor with not shield. These percentages can be converted into target numbers. Here I converted these into the number one would need to roll on 2d6, since this is the type of roll used in Chainmail.

AC 9 and AC 8: 7
AC 7 and AC 6: 8
AC 5 and AC 4: 9
AC 3: 10
AC 2: 11

Since the range of results is fairly limited using only 2d6, there is not much variation in targets. These are really approximations of the true average odds, but I think they are the best approximations we can have. Here’s the same table with target numbers using the more familiar (and more granular) d20.

AC 9: 10
AC 8: 11
AC 7: 13
AC 6: 13
AC 5: 14
AC 4: 15
AC 3: 18
AC 2: 19

Basically, we have the standard combat table for 1st level characters, with the exception of AC 7 and the jump to plate mail.  I think this goes to show that Gygax and co. were either very careful to map out the combat table so that it fit with Chainmail, or very careful when writing Chainmail in the first place to have a steady progression. I believe the jump between chain & shield and plate mail is a product of the bell curve distribution of 2d6 versus the linear distribution of the d20, and likewise with the blip at AC 7.

So that’s everything you need to fight those fantastic creatures and bears and whatnot. Roll a die, find their AC, and see if you score a hit! Then, of course, roll 1d6 damage and deduct it from the opponent’s hit points. Rinse and repeat. Soon I’m going to write a post looking at the weapon modifiers, once I figure out how to make nice-looking tables. That’s where things get interesting.

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