Me and the DMG

[squeen]

Here's another table for this crazy thread. I've double-posted it over an K&KA, so sorry if you are reading it twice.

There's a rule about helmets in 1e/AD&D that says if you choose not to wear one, then an intelligent attacker (in close quarters) will aim for your unarmored (AC 10) head with 1 in 2 attacks. The random chance (unintelligent attacker) of getting hit is 1 in 6 plus a hit vs. AC 10 (nekid). So I wondered what affect on your effective (total) AC this AD&D rule has.

NOTE: There's also a rule in AD&D that says you have to remove your helmet to listen at doors. I think they kind of go together.

The rest of the post is copied from the thread on K&KA:
----------------------------------

So, my self-answered question related to this topic is thus:

You are Frodo wearing a mithril chain-shirt (AC 0?), but no helmet...

What's your effective AC in AD&D?​

I wrote a small program in my home brewed MATLAB clone and performed 20,000 trails, using the to-hit tables in the 1e DMG and the 20-always-hits rule. I then looked at the 1 in 6 change an unintelligent creature will accidentally strike at your naked (AC 10) head, and then finally with a 50% chance an intelligent monster will go directly for your bare noggin.

Here's the result if you are being attack by a 1 HD monster, e.g. Frodo gets attacked by an Orc


This basically says that for anything below leather, not wearing a helm has little effect (as expected). That means Merlin in the old Excaliber movie was sporting a metal skullcap presumably to just hide his bald spot.

Around chainmail class AC, forgetting your helm at home starts to hurt you. Versus an unintelligent 1 HD monster, you loss about 1 AC point of protection. Versus an intelligent attacker, you lose about 2-3 points of AC.

In plate mail w/ shield, you lose -1 AC vs. the foolish, but a whopping -4 AC against the wise.

If you are Frodo fighting the Orcs in Moria, and you are more concerned about keeping your armor class a secret from your allies than staying safe, then your awesome body AC of 0 (or even -2) drops to AC 2 (plate+shield) versus a stupid orc, and to AC 5 (chain) versus a smart one (up close).

The spear chucking Orc in Moria, shouldn't have used a missile weapon --- because he, like Thor against Thanos, "should have gone for the head." (I'm sure that, has he lived, Sauron would have made the finer points of combat clear to him at his annual performance evaluation.) Thor too learned his lesson, and held on to his axe for the sequel.

What about higher HD monsters, you ask?

Here's the chart for a 4 HD attacker


You see the attack matrix hasn't really changed much --- it's just biased upwards by 5% x HD, or +20%, but the always-hit-on-20 curve-flattening effect disappears from the extremely good AC results.

Still, let it soak in. AC -2 without a helmet vs. an above-average Ogre:
--> 50% chance of being hit

How about AC -2, no helm, versus a genius Troll (6 HD) with three attacks per round???
--> it's 60% to-hit per attack (40% miss) which works out to be a 1-0.4*0.4*0.4 = 93.6% chance of it landing at least one blow!

Compare that to just a 65.7% chance it would have against you if you weren't so image-conscious!

So...

I've got this thief with an elven chain-mail shirt. He says he doesn't wear a helmet.
How should I indicate to him that it's hurting his AC?

1. Start describing that the smart monsters are taking head-shots at him?
2. ...or just show him this chart?

 

[squeen]

I'm going to add one more patronizing comment related the 1e DMG --- imagine if such a table had been included originally?
Would anyone have been confused, ignored, or forgotten the helmet rule?

I think Graphics really help to drive a point home, and make it stick in our minds.

So, since this is a forum about Adventure and Product Design --- a take away:

Good presentation is fundamental to good communication.​

(Agreed? Good. Now, go head and keep skipoing over the posts about icons and other formating tips over in the Illusion thread. [/rant])

 

[DangerousPuhson]

(Agreed? Good. Now, go head and keep skipoing over the posts about icons and other formating tips over in the Illusion thread. [/rant])

Why don't you just tell your player "you know there's a rule about helmets affecting armor class, right?", and if he doesn't listen then he can live with the choice he's made? You'd probably get more response to your posts if they didn't seemingly over-complicate what most would consider a pretty straightforward situation... I get that you're keen to dissect every facet of the game and really get into the number-crunch mechanical grit of the rules, but I think you might be overestimating the amount of people on here who are similarly motivated.

When the forum touts "adventure design", it doesn't mean the same thing "system design". I think more people are here to discuss the former rather than the latter, and so you'll see more participation in threads dealing with the former over the latter. Exception: arguments seem to bring the boys to the yard, so maybe if you start an argument about what you want to talk about you'll get the active participation you crave (I do not recommend this approach, for sanity reasons).

It probably doesn't help things to see a veritable TED Talk on the subject culminate into a common-sense adage like "Good presentation is fundamental to good communication" either. Just saying.

 

[squeen]

I posted the tables here (after the K&KA) because---while I realize very few folks (here) care much about 1e rules and their implications---I thought of a way to try and tie it in to the following:

1. the topic of this thread (i.e. dissecting the 1e DMG a.k.a. understanding AD&D System Design)
2. Formatting which I believe should be front-and-center as a part of Adventure Design

Truthfully, I am not sure what to make of the fact that Obsidian Keep seems to have sucessfully impended (verbatim!) the Formatting suggestions we hammered out in the Bryce Says thread. It seems too much of a coincidence to have been a case of convergent design. Not surprisingly, Bryce rated it 9/10 --- I believe he not-so-indirectly had a hand in it.

You are correct about one thing, controversial statements (like the small chide at the end of my last post) seem to elict more of a reaction than detailed content.

Que sera sera.

 

[Pseudoephedrine]

I'm going to add one more patronizing comment related the 1e DMG --- imagine if such a table had been included originally?
Would anyone have been confused, ignored, or forgotten the helmet rule?

I think Graphics really help to drive a point home, and make it stick in our minds.

So, since this is a forum about Adventure and Product Design --- a take away:

Good presentation is fundamental to good communication.​

(Agreed? Good. Now, go head and keep skipoing over the posts about icons and other formating tips over in the Illusion thread. [/rant])

Just to be salty for a moment, I do wish core rulebooks of games had more diagrams and fewer illustrations. I don't really need more generic fantasy art, but a flow chart of a process, a map with a proper scale, or a well-designed graph are all extremely useful, and I wish more games included them.

 

[Beoric]

The spear chucking Orc in Moria, shouldn't have used a missile weapon --- because he, like Thor against Thanos, "should have gone for the head."

Um. no, Frodo concealed the chain shirt, so there would be no reason to take more head shots.

I remember this rule. I would say that if you want to use the rule, where it is obvious that the character has an armored body and unarmored head, I would (a) point out that his head was unarmored, and (b), start taking more shots at the head. I would also impose visibility/hearing restrictions because of wearing a helm (IIRC there is a companion rule somewhere that talks about a great helm doing this but being a better AC that plate), so this is a real choice.

I should mention, I never liked the rule because I didn't think an unarmored head should have a 10 AC. It is a smaller target than "anywhere in the body", and is more easily protected by shields, arms and weapon parries. This is my problem with every "called shot" system I have seen. For example, if you are wearing a chain shirt without chausses or grieves, should there not be more attacks to your unprotected legs (which in this case would also not get a shield bonus). Should attacks against the legs never get a shield bonus unless using a kite shield? If that same chain shirt is short sleeved, do I get attacks against the arms? If I am not wearing gauntlets or muffs, should there be a chance of losing a finger? Should that chance be larger if my weapon has a decent guard? Is a guard better than quillons? I am afraid the minutae can become unplayable.

And unlike DP, I do like these conversations, and even started a thread for the purpose of having them.

 

[squeen]

All great points--especially about the arms/hands. A Great Helm was suppose to give +1 AC to plate+shield for a total AC of 1.

What I thought was interesting about running the stats BtB was the effect of that 1 in 6 (or 1 in 2) along with the AC 10.

Is an AC typically worse by 1-2 points against a "nekid noggin" reasonable? Everything basically dropped one armor style (plate to chain, chain to leather, etc.). I thought ol' EGG's math worked out decently.

In retrospect, perhaps your thread would have been a better place for this.

Well, +1 for Byrce's Forum --- just crickets over at K&KA so far. (EOTB to the rescue)

 

[Beoric]

I have gone through the exercise of assigning a value to each piece of armor representing how much of the body it covers, and assigning fractional AC to each. I could then add up the AC of the various parts, and calculate what happened if you were in plate, but gave up your vambraces in favour of (leather) bracers of brachiation; took of your sabatons to don slippers of spider climbing; and took or your helm to wear a cap of I-can't-remember-the-name-of-a-cap-right-now. I didn't worry too much about accuracy, I just wanted some sort of model of the impact for every type of armor piece that might be replaced by a magic item.

 

[Beoric]

I have gone through the exercise of assigning a value to each piece of armor representing how much of the body it covers, and assigning fractional AC to each. I could then add up the AC of the various parts, and calculate what happened if you were in plate, but gave up your vambraces in favour of (leather) bracers of brachiation; took of your sabatons to don slippers of spider climbing; and took or your helm to wear a cap of I-can't-remember-the-name-of-a-cap-right-now. I didn't worry too much about accuracy, I just wanted some sort of model of the impact for every type of armor piece that might be replaced by a magic item.

Is an AC typically worse by 1-2 points against a "nekid noggin" reasonable? Everything basically dropped one armor style (plate to chain, chain to leather, etc.). I thought ol' EGG's math worked out decently.

It's good enough. What interests me is whether there is an actual choice to be made, ie some sort of downside to wearing a helmet. If not, then the players will always wear one, and the rule become pointless because it will never be engaged.

 

[squeen]

It's good enough. What interests me is whether there is an actual choice to be made, ie some sort of downside to wearing a helmet. If not, then the players will always wear one, and the rule become pointless because it will never be engaged.

That's it exactly! The no-helmet benefit of listening at doors + increased visibility.

Would you also be tempted to modify the chance of surprise?

 

[Beoric]

That's it exactly! The no-helmet benefit of listening at doors + increased visibility.

Would you also be tempted to modify the chance of surprise?

IIRC, it is only the great helm that gives the bump to AC and is called out as restricting visibility. An ordinary helm (which I think was illustrated on one of Gary's DM supplements - you know, the one with the pictures of the armor and polearms) is basically an iron cap with nasal, and doesn't restrict vision at all.

So it really isn't a trade off, except for removing the helm to listen at doors (which was really a way to create a risk of ear-seekers because Gygax was annoyed at the listen-at-door pixel bitching which his own DMing style had created). Pro tip: after you listen at the door, assuming you are the fighter and not the thief who actually has a skill to do that, put your helm back on.

I can't remember enough about the surprise rules to know if you should modify surprise. If surprise is really more of a party thing, I think it might be cancelled out by the other members of the party who aren't wearing helms - like the MU, or the thief (who as you pointed out doesn't really suffer an AC penalty). Also, a modification to a d6 roll is a pretty big hit to take, depending on the type of helm. Also, I thought you started from the premise of implementing the rules as written, which premise would be defeated if you had to create houserules to make them work properly.

 

[squeen]

Also, I thought you started from the premise of implementing the rules as written, which premise would be defeated if you had to create houserules to make them work properly.

Yes. Seems like someone has to periodically talk me down from my D&D-mod-ing fugue-state.

It's a thing, though --- learn a new rule...really understand it and it's place in the larger scheme...

...and then you've got this hammer and everything looks like a nail.

 

[Beoric]

Hey, I think you always end up drifting toward modding for a good reason. When you understand where something works in the grander scheme, you also start to see where it doesn't work. But I support your RAW experiment.

EDIT: I would rephrase that if I could figure out how.

 

[squeen]

NOT that I'm doing it...

...but move surprise from d6 to d8. 3 in 8 (37.5%) with helmet, 2 in 8 (25%) without.

Compared to 2 in 6 (33.3%) BtB. It's a minor shift to the character wearing a helmet, and a small advantage to the ones without. The deal breaker is that it's a party effect...as you stated.

NOT that I'm doing it...

 

[Beoric]

You could also apply it to other 1e perception skills, like searching for secret doors. NOT that you are doing that.

 

[Beoric]

@squeen and @EOTB I have a question for you. I have two orcs. Per the MM I roll for weapons: one has an axe, the other has a polearm. The entry for AC is 6.

Is the AC because of their natural qualities (hide, dexterity, etc) or because they have armor?

If armor, does this assume they are using a shield (plus ringmail or studded leather) or no shield (scale only)?

If it assumes a shield, is the orc with the polearm actually AC 7 because he needs both arms for his weapon and cannot use a shield; or do we assume he has slightly better armor (scale)?

 

[EOTB]

AC in the MM wasn't updated to the AC10 scale yet; it was still using the OD&D AC9 scale. So if a DM wanted, all ACs could be worsened by 1. I don't mess around with the adjustment (since it would be constant and I'm not interested in giving up decades of ingrained muscle-memory).

So the entry is the equivalent, for armor-determining purposes, of AC 7 - leather and shield, or studded leather. I say it's leather for WvAC purposes, and on an orc leather and shield is AC 6 instead of 7. Monsters are tougher in a way I don't care to define, and don't feel compelled to define, then a PC wearing leather. But again this is DM choice.

For polearm-using orcs, the DM is justified in dropping it to AC 7 (or 8). The DM is also justified in keeping it at AC 6 (or 7); perhaps polearm-wielding orcs wear studded leather.

It's really just up to the DM. But yes, whatever adjustments they make, they should be aware of the AC9 base in the MM, so they're making adjustments purposefully.

 

[squeen]

I had always mentally been in the AC9 system, but noticed there had been a shift.
When exactly did the AC10 change occur?

Agree with EOTB. Monster AC is a knob the DM is allowed to turn fairly liberally as the situation requires.

For example, I've put skeleton (hiding) inside suits of plate mail to toughen them up. I did not overthink the mechanics. They were just AC 2. You also seen I've haste-ed skeleton and given them an AC bump there too. This (excessive?) willingness to tweak and invent probably marks me as an OD&D-er, and is why I have had such a strange relationship with 1e. I am attracted to its rigor, but too easily wander off melody in an improvisational fugue. Gygax codified AD&D to reign-in nutjobs like me (and I'm thankful for it).

Conversely, Finch's observation in S&W (unabashedly 0e) that rules for PC's don't apply for monsters/NPCs is also a bit liberating if you like. Sometimes we DMs need that kind of permission too.

Still, the simulationist in me acknowledges that the 5% difference in AC probably matters more statistically in mass combat situations than in a single encounter.

Not terribly helpful. Sorry.

Thanks for reviving this thread. Consider this it's central theme: AD&D appears, on the surface, to have rules for every contingency --- but that's not actually true. What it provides is a surprisingly well-considered, complete, inter-locking, and functional system for the most common occurrences, and guidance for many, many special cases. Still, the DM is encouraged to use good judgement and be inventive to bridge the gaps.

To my eyes, its a Masterpiece of game design. Unequaled since. And just like there is no perfect painting or sculpture, it has flaws....but I find I can happily live with them.

 

[Beoric]

AC in the MM wasn't updated to the AC10 scale yet; it was still using the OD&D AC9 scale. So if a DM wanted, all ACs could be worsened by 1. I don't mess around with the adjustment (since it would be constant and I'm not interested in giving up decades of ingrained muscle-memory).

Gygax apparently didn't worry about the adjustment either, since he uses the same AC in Appendix E of the DMG, and (I checked) in later modules like Tsojcanth.

EDIT: The reason I ask is because of my ongoing quest to convert 1e monsters to 4e, and make them as close as I can get to exactly as hard a challenge in 4e as you would expect them to be in 1e.

 

[EOTB]

Yeah, he never updated the AC of MM monsters, even through they were created on an AC9 base. But if you're trying to figure out what armor a MM monster is considered to be wearing, using the PHB/DMG armor/armor class relationship will be off by 1 AC. That's it.

As far as module conversion goes, I would keep the AC the same if challenge is the goal. Narrate whatever armor you think is best for the same AC.