A historical look at D&D ACs (part 1)

[trancejeremy]

Right, but OTOH those super low ACs weren't likely to factor in a whole lot. Most creatures in that category weren't going to be defeated by the fighters hacking at them anyway. They were going to go down to magic, and probably not even by direct magical attack, but by 'indirect' means (IE like dropping a wall on them or collapsing the ceiling of a cave, or sticking them fast with rock to mud, etc). Heck, things like demon lords all have practically unlimited teleportation and/or gating capability. At best your post level 12 fighters might manage to be in for the final kill once the monster was somehow disabled in some way.

So, yes, melee combat in a sense 'breaks down', but it hardly matters. No sane wizard would stick around to play pokey with a monster in the deep sub zero AC category if all they were going to be doing was sticking it with their dagger. That would be true even if the monster's AC was 2 in all likelihood.

I disagree - while you point out that direct magical attacks weren't terribly effective (because of the high magic resistance of such monsters), most high level fighters had a nice magical weapon and probably some sort of strength enhancing item (ie, Girdle of Giant Strength)

Say for instance, a 13th level Paladin with a Holy Avenger and a Girdle of Frost Giant Strength. That would be +9 to hit with a THAC0 of 8, so while he'd need an 18 to hit AC -10, he'd only have to roll a 9, which is more often than not. And since they'd get two attacks per round, would probably be hitting it once per round.

And the damage would likely be 1d12+10 (for being Holy Avenger vs a Demon, in Lolth's case) + 9 for strength. So 20-31 points of damage.

I actually just went through the module The Forgotten Temple of Baalzebub for OSRIC (a high level module ironically with a lot of demons in it) with said Paladin (as well as a 12th level Fighter with a Sun Blade) and they really cleaned up (since most didn't have ACs anywhere near -10).

edit:

And bear in mind, Teleportation in AD&D carried some risk, it wasn't something you would want to do unless it was an emergency as it has a chance of killing you (getting caught in the ground) (until Teleport Without Error came along)

 

[AbdulAlhazred]

I disagree - while you point out that direct magical attacks weren't terribly effective (because of the high magic resistance of such monsters), most high level fighters had a nice magical weapon and probably some sort of strength enhancing item (ie, Girdle of Giant Strength)

Say for instance, a 13th level Paladin with a Holy Avenger and a Girdle of Frost Giant Strength. That would be +9 to hit with a THAC0 of 8, so while he'd need an 18 to hit AC -10, he'd only have to roll a 9, which is more often than not. And since they'd get two attacks per round, would probably be hitting it once per round.

And the damage would likely be 1d12+10 (for being Holy Avenger vs a Demon, in Lolth's case) + 9 for strength. So 20-31 points of damage.

I actually just went through the module The Forgotten Temple of Baalzebub for OSRIC (a high level module ironically with a lot of demons in it) with said Paladin (as well as a 12th level Fighter with a Sun Blade) and they really cleaned up (since most didn't have ACs anywhere near -10).

edit:

And bear in mind, Teleportation in AD&D carried some risk, it wasn't something you would want to do unless it was an emergency as it has a chance of killing you (getting caught in the ground) (until Teleport Without Error came along)

Eh, funny that you should mention that, Deities and Demigods lists one of her 'at-will' powers as Teleport Without Error. So really, no melee combatant represents even the capability of a real threat to our spidery friend. Even assuming you were to encounter her alone, outside of any location she controls, she has a 100% chance of summoning a considerable number of spiders, so our friend the paladin is going to have a tough time even getting close. She's got a good chance (66%) of summoning up one of a variety of types of demon as well, which should keep our Holy Avenger wielding friend quite busy. While having 66 hit points she's also got heal 3 times/day, so effectively something north of 120 hit points if things are going her way (and with TWA there's no reason she'd not be able to take a round to get to somewhere safe and use that as needed). These (and a long list of others including Confusion) are all 'SLAs', thus presumably not interruptable and available in spider form. If she chooses to manifest her drow form then she's also a 16th level priest and a 14th level wizard, so you can expect a good bit more nastiness.

It isn't that melee combatants aren't potentially effective, they are. It is more that whether or not they can do substantial damage isn't necessarily all that relevant. In the vast majority of cases there's simply no chance they're going to decisively defeat beings of Lolth's power level (and she's really rather anemic for a demon lord). If you were looking at say Demogorgon it becomes more apparent, nobody is going to do real major damage to it in one round with a sword.

Now, it is interesting to look at how Lolth evolved. In 2e an 'Avatar of Lolth' is pretty similar in powers to the 1e version, but has an AC of -6 and 128 hit points. I think there was some degree of effort to make a wider range of fun interactions with these sorts of monsters, a trend which seems to continue in 4e where hitting Lolth really isn't a huge problem, her hit points are on par with other similar demon lords, and her powers are considerably less on the lines of "you non-casters are boned."

 

[Cerebral Paladin]

This analysis points to a feature of flatter math: AC ranges have to contract for flatter math to work. In the earliest examples, the math was pretty flat for characters besides fighters, but that worked because the AC range was narrow--roughly 9-2 (=roughly 11-19 in modern reckoning). I'm not saying that nothing should be better than plate + shield, but it does suggest that the range between the worst common armor class and the best common armor class shouldn't be more than 7 or 10 points, maybe stretching to 12 or 15 for high-level monsters because the math won't be perfectly flat. But that suggests that a range of 7 or 9 points between unarmored and plate + shield (all mundane) may be too big.

 

[Iosue]

I just wanted to bump this thread and make a contribution, particularly because I haven't been able to find Part 2.

Here's how things roll in B/X and BECM (Immortals is a whole other kettle.)

In Moldvay, the to-hit table goes from AC 9 to -3. The monsters range from AC 9 to -2 (Gold Dragon). Although Green Slime can always be hit. The average monster AC is 5.4, the median AC is 3.5, and the mode is AC 6 with 22 monsters. Most monsters are in the range of AC 7-5.

In Cook/Marsh, the to-hit table again goes from 9 to -3. The monsters range from AC 8 to -2. Here the average is now AC 4.2, the median is still 3.5, and the mode is also AC 4. Most monsters are in the range of AC 6-3.

Mentzer Basic skews a little easier. The player to-hit table goes from 9 to -1, but the monster to-hit table goes to -5. Monsters range from AC 9 to -2. Average AC is 5.5. The median is 3.5, and the mode is AC 6 again, with 23, and again most monsters fall in the AC 7-5 range.

Menzter Expert seems to have a much wider range. The to-hit table goes from AC to -9. Monster to-hit is AC 9 to -6. Monsters remain in the range of AC 9 to -2. Average AC 4.2, and median AC 3.5, just like Cook/Marsh. But mode is AC 7/4/2, each with 13, and most monsters fall in the range of AC 4-2 (36 monsters) and 7-5 (35 monsters)

Things take a turn for the harder to hit in the Companion rules. Player to-hit tables now go from AC 9 to -13. Monster to-hit tables go to AC -20. Thanks to the Other Planes list, monsters range from AC 9 to -10 (15-16 HD Elemental). Average AC is now 1.5, the median AC is now -0.5, and the mode AC is 0/-4, both with 7. Most monsters fall in the range of AC -2 to -4 (20 monsters), with a secondary range of AC 0 to -2 (17 monsters).

In the Master set, we find the Big Tables of Player To-Hit and Monster To-Hit, both of which cover all levels/HD, and go from a Spinal Tappy AC 19 to -20. The higher AC numbers are apparently to represent penalties due to Dexterity or magical penalties. Monster AC ranges from AC 9 to -15 (73-80 HD Elemental Rulers). The Average AC is 1.4, the median AC is -2.5, and the mode is amazingly AC 5 with 10 monsters (AC 0 has 9 monsters). Monsters clump in the AC 6-4 range (27 monsters), although there are also 27 monsters with AC 0 or better.

One thing that was really obvious with this is the extreme no-love for AC 1. Out of 511 monsters listed in Moldvay, Cook/Marsh, and Menzter, only 10 have AC 1. By comparison, 47 have AC 2, and 26 have AC 0. Even AC 9, at the opposite end, has 26. Companion has the most AC 1 monsters, with 4, while the Master set has zero AC 1, while having 9 monsters with AC 0. It's weird, wild stuff.

Anyhow, one reason I wanted to look at this is because BECM represents the widest range of TSR D&D, from dungeon crawling in the low levels of Basic to the utter gonzo stuff going on in the Level 30s of Master. If we cut out the AC 19-10 stuff as more easily handled by situational bonuses (no monster in BECMI or B/X has worse than AC 9), I think you basically need to cap AC at 30, and cap to-hit bonus at 20 at the most. The 34th-36th level BECMI fighter needs a 12 or better to hit an 80 HD Elemental Ruler, which is actually 9 or better, since they can only be harmed by +3 weapons or better.* By comparison, the highest monster AC in 4e is Bahamut with AC 52, which presumes a attack bonus of 42 to get just a 50/50 chance of hitting him.

*Just to illustrate how gonzo BECMI could get, an 80 HD Elemental Ruler is 160' tall, has an average of 360 HP (I don't think there's a DM alive who'd want to give them the full 640 possible), any strike by one is a Save vs. Death Ray or be crushed instantly (making your save means you take "only" 12-144 damage; 36th level Fighters with 18 Con have max HP of 153), they are immune to 1st through 5th level spells, poison, all charm, hold, mental attacks, illusions, and instant death spells, and they save as 36th level Fighters, which means they only miss the save on a 1. These guys just scream adventures of "Find the magic sword that does 3d10 damage to elementals and give it to the Fighter.")

 

[Badapple]

I remember playing low level D&D Basic and having fighters with 13 dex and plate and shield having an AC of 1 and the monsters all needing around an 18+ on the die to hit them. I remember once I got my fighter a magic shield or magic plate he would often only be hit on a 20 in fights against swarms of orcs or goblins or bandits. Tougher monsters would regularly miss my character even if they rolled a 16 or so.

Meanwhile the Fighter, with say a +2 bonus to hit from strength, needed around a 12+ on the die to hit the AC 5 or AC 6 monsters...

In other words, there was a pretty wide disparity between what my PC needed to hit the bad guy and what the bad guy needed to hit my character. My character tended to be missed a heck of a lot of the time, but when he was hit, he usually lost a higher percentage of his hit points and healing tended to be rarer to come by. (Clerics didn't even get access to spells until second level and they didn't get wisdom bonuses to spells) Not advocating either for or against this, just remembering it. I find it interesting on all these playtest threads where the DM is complaining that the monsters keep missing the players and want all monsters to get around +2 additional to hit as tuning.

 

[MerricB]

I just wanted to bump this thread and make a contribution, particularly because I haven't been able to find Part 2.

Yeah, sorry about that - life has interfered.

Cheers!

 

[AbdulAlhazred]

This analysis points to a feature of flatter math: AC ranges have to contract for flatter math to work. In the earliest examples, the math was pretty flat for characters besides fighters, but that worked because the AC range was narrow--roughly 9-2 (=roughly 11-19 in modern reckoning). I'm not saying that nothing should be better than plate + shield, but it does suggest that the range between the worst common armor class and the best common armor class shouldn't be more than 7 or 10 points, maybe stretching to 12 or 15 for high-level monsters because the math won't be perfectly flat. But that suggests that a range of 7 or 9 points between unarmored and plate + shield (all mundane) may be too big.

It really isn't all that much flatter. Fighters have STEEPER math in AD&D than in 4e, they get +1/level automatically, plus whatever items and etc they acquire. Clerics get +2/3 level automatically, thus they will almost match 4e's curve with a modicum of added bonus, say a +2 weapon by 9th level, not exactly a stretch. Magic users are irrelevant as they have no need for to-hit bonus. Thieves are getting +1/2 level, which makes them basically the only class below the 4e curve that matters. Even there they surely will get some magic to make up part of it. I'd say this is the main reason the AD&D thief is frankly a weak class.

It is true that ACs vary less in AD&D than in 4e, but the end result is basically you have PCs starting out needing 16+ to hit at level 1 typically, and progressing to much easier values from there on out. Also it is basically a 20 level system, so that removes a good chunk of progression right there.

 

[MerricB]

In other words, there was a pretty wide disparity between what my PC needed to hit the bad guy and what the bad guy needed to hit my character. My character tended to be missed a heck of a lot of the time, but when he was hit, he usually lost a higher percentage of his hit points and healing tended to be rarer to come by. (Clerics didn't even get access to spells until second level and they didn't get wisdom bonuses to spells) Not advocating either for or against this, just remembering it. I find it interesting on all these playtest threads where the DM is complaining that the monsters keep missing the players and want all monsters to get around +2 additional to hit as tuning.

I recently came up with a 70/30 rule:

The 70/30 Rule: Players should succeed 70% of the time, and enemies should succeed 30% of the time.

It comes from my observations of play recently. I really hated being hit on my good defense in 4e most of the time, especially when I'd concentrated on it. Meanwhile, I wanted my own actions to succeed.

Cheers!

 

[Iosue]

Oh, here's a total BECM overview of # of monsters by AC:

AC 9: 17
AC 8: 8
AC 7: 39
AC 6: 47
AC 5: 42
AC 4: 34
AC 3: 23
AC 2: 24
AC 1: 6
AC 0: 21
AC -1: 4
AC -2: 11
AC -3: 2
AC -4: 4
AC -5: 2
AC -6: 4
AC -7: 1
AC -8: 3
AC -9: 2
AC -10: 2
AC -11: 1
AC -12: 2
AC -13: 1
AC -14: 1
AC -15: 1

Mean: AC 3.15
Mode: AC 6
Range of majority: AC 7 to 4 (162 of 313 monsters)

Also there is one monster list that I didn't include. In the Master Set, there's a collection of simple stat blocks (no descriptions) of any monsters from older editions, adventures and the like that hadn't been included in BECM to that date. I didn't include it, mostly because it's a pain, but also because it seemed to follow the same trends as indicated above, and had no negative ACs beyond -15.

 

[MerricB]

It really isn't all that much flatter. Fighters have STEEPER math in AD&D than in 4e, they get +1/level automatically, plus whatever items and etc they acquire. Clerics get +2/3 level automatically, thus they will almost match 4e's curve with a modicum of added bonus, say a +2 weapon by 9th level, not exactly a stretch. Magic users are irrelevant as they have no need for to-hit bonus. Thieves are getting +1/2 level, which makes them basically the only class below the 4e curve that matters. Even there they surely will get some magic to make up part of it. I'd say this is the main reason the AD&D thief is frankly a weak class. .

Note also that the thief advances faster than the cleric and fighter, so the disparity isn't as bad as you might think.

Here's a list of the THAC0s at key XP points:

0 XP: Cleric 20, Fighter 20, MU 21, Thief 21, MU 21
5,000 XP: Cleric 20, Fighter 18, MU 21, Thief 21
10,000 XP: Cleric 18, Fighter 17, MU 21, Thief 21
20,000 XP: Cleric 18, Fighter 16, MU 21, Thief 19
40,000 XP: Cleric 18, Fighter 15, MU 19, Thief 19
80,000 XP: Cleric 16, Fighter 14, MU 19, Thief 19
120,000 XP: Cleric 16, Fighter 14, MU 19, Thief 16
150,000 XP: Cleric 16, Fighter 13, MU 19, Thief 16
200,000 XP: Cleric 16, Fighter 13, MU 19, Thief 16
300,000 XP: Cleric 16, Fighter 12, MU 19, Thief 16
400,000 XP: Cleric 16, Fighter 12, MU 19, Thief 16
500,000 XP: Cleric 14, Fighter 11, MU 19, Thief 16
700,000 XP: Cleric 14, Fighter 11, MU 16, Thief 14

As you can see, the disparity between the cleric and the thief isn't actually that bad - and even the fighter rarely opens up much of a lead. In 2E, the 19->16 jump isn't there for the thieves and MUs, but they start at THAC0 of 20 instead. The thief also has the possibility of the backstab - a +4 to hit - which brings their effectiveness close to that of the fighter.

The fighter's curve is very slightly ahead of that of 4E - getting a +2 weapon at ninth is by no means assured, and the only other means of increasing your attack bonus would be the rare Gauntlets of Ogre Power or Girdles of Giant Strength. (Of course, it's way, way behind that of 3E, which is one of the reasons that Pathfinder is - for me - a lot of great material built on foundations of sand).

The biggest problem with the thief in AD&D simply comes from their ludicrously low chances of success at low levels. With only a 20% chance of finding and removing traps at first level, why are they with the group? At higher levels, magic begins to tread on their toes.

Where the AD&D system begins to break down is at the very high levels (11+), but it serves pretty well before then in my opinion. However, negative monster ACs do serve to point out the flaws in the system.

Cheers!