As long as Armor Class is a thing, I prefer descending armor class to ascending. I’ll explain.
In terms of ease of use, ascending is better. The math is easier. It’s easier to add than subtract. You know this is true intuitively even if it’s not strictly true for you. You see it among your friends. Ascending AC says, “add your attack bonus to d20 and compare.” So that’s a real easy mechanic. It’s easier than subtracting an armor class from your THAC0 and comparing. So in that sense ascending is better - it’s easier.
But there are two things that make descending AC better than ascending.
The first one has to do with bounded accuracy and the arms race that happens with skills and stats in more modern editions.
In D&D games prior to 3E, there were only 20 (or 21) armor classes. Just 20. There was AC 9, which was the worst, up to AC -10, which was the best. You couldn't get any better than the equivalent of AC 29 in an ascending system.
But in the ascending systems of 3E and subsequent versions, your AC can go sky-high. You can have an AC of 40, 50, 100. What does that mean? It means that if someone wants to have a reasonable chance hit you, they need an attack bonus of some astronomical number as well. And the same is true for the DM's creations: Super high AC and super high BAB (base attack bonuses).
Not so in descending. There's little reason for super inflation of attack bonuses because even an ancient red is only going to get up to a little less than AC 29.
The second thing that makes descending AC is related to the first, but it's more of a player-side aid. That is, with only 20 steps to the AC scale, you can chart it very easily and put it where everyone can see it. It can be reduced to a chart rather than a math problem. Here is the entire range of AC versus attack roll results in Mythical Journeys. This chart is based heavily on 0D&D:
Players
Monsters
That's it. No math and very simple charts. Click to enlarge as usual. Obviously the part that goes from -1 to -10 is missing here but it would be trivial to show it as well.
So you can actually make these math problems into charts for the math-challenged. After using them for one session, they will be really easy to use.
Of these two reasons, I would say the bounded accuracy of descending AC is more important than the ease of its use because it kills off the arms race. It also means a guy at level 4 is not all that much better than a guy at 1, and not that much worse than a guy at 8. The difference is in resources (hit points, money) rather than in personal skill. And that keeps the characters feeling more realistic and less like superheroes.
Why can't descending AC go to -20 or -40 or -100. It is just an arbitrary limit. A DM using ascending AC can just as easily limit AC to 29 as a DM using descending AC can let AC go as low as he wants.
ReplyDeleteHi Steven, thanks for the vine.
DeleteYou know, you're right. You could just go to -20 if you want and you could stop at AC 29 if you want to as well!
Maybe it's just my personal bias then?
But what happens when you bring that character with the unusual AC to another table? I guess that's pretty rare too.
Monsters could. Great wyrms could have -15 or so. Only players where limited to -10
DeleteAgreed. I'm obviously biased but I have a lot of difficulty adding attack bonuses and a bunch of extra pluses. I can do thaco in my head.
ReplyDeleteOMG I'm totally backwards from that - but the chart works for everyone
DeleteDescending AC and the roll result/AC/chart comparison means never being confused about how golf scores work. An underrated bonus to the system.
ReplyDeleteLMAO thanks for the vine
DeleteRecently, I decided to cap the ascending AC in my games to 20. A 20 AC is the max. So, that solves one problem.
ReplyDeleteRight, because you're a designer you would be thinking through these issues a little more deeply. How do you handle the arms race on to-hit rolls?
DeleteOn the one hand, maybe you don't put artificial limits on it. Sky's the limit. The GM has to keep that in mind when doling out treasure. On the other hand, maybe you cap it at +10. Or possibly +10 for everyone but fighters, they can go up to +20. Thoughts?
DeleteLet me concentrate on the last part of what you said. It is important to give fighting men an advantage in some area, and combat might as well be it.
DeleteAt my own table, I give them charisma-themed advantages. More people want to follow fighters than the other weirdos. They're more loyal. Fighters, being good at fighting, can scare off lesser beings. That sort of thing.
One of the new school terms that's come up in the last five years is "bounded accuracy," Maybe more than five years, but I'm old and everything seems to be happening all at once now. I'm revulsed by most new school stuff but this term I like (along with advantage rolls.)
I like the idea of a veteran being in the same league as a Hero and a Hero in the same league as a Super-Hero, and the highest-level guy in the world being like level 12. So numerical bonuses, even small ones, seem much bigger.
Therefore it's quite important to me in my game philosophy to keep the numbers small overall. I don't want a PC with AC -6. That should be the realm of the enemy warlord or even dragons.
It's worth mentioning that 5th edition D&D features bounded ascending armor class. The primary scale is AC 10 to AC 20, and while it's possible to pass AC 20 via magic (much in the same way that it's possible to pass AC 0 via magic in OD&D), it's not easy, and you will never pass it by any significant margin. No monster in the Monster Manual has an AC higher than 20.
ReplyDeleteAscending AC is functionally identical to OD&D's descending AC. The thing that determines whether or not the system is bounded is the how generous the rules are when it comes to handing out bonuses. AC was mostly fixed, and only ever increased if you found a magic item. Your THAC0 increased with level, but not by a lot. A 10th level fighter has a THAC0 that's only 7 better than a 1st-level fighter. Again, magic can increase that further, but in general the attack rolls improve on a relatively limited scale, and as a result there is no need for the sort of AC "arms race" like the one you see in 3rd and 4th edition.
5th edition is similarly stingy with attack bonuses. A 10th level fighter has a +4 proficiency bonus that they can add to their rolls to hit, but that's only 2 higher than what a 1st-level fighter gets. The fighter maxes out at +6, at 20th level. That's a *really* shallow progression--even compared to OD&D (which gives fighters the equivalent of +7 at 10th level). They balance it by granting larger bonuses for high Strength scores, so a 1st level fighter in 5e actually has a better chance to hit (and does better damage) than a 1st level fighter in OD&D, but a 5e fighter also improves less as they level than does an OD&D fighter. The net effect is the same--attack rolls improve only marginally with level, and therefor the game can use the same AC scale at any level of play.
5e further limits bonuses to both AC and attack rolls with their "attunement" mechanic. Powerful magic items (including pretty much all the ones that grant AC and attack roll bonuses) have to be attuned to your character, and a character can only ever use three attuned magic items at a time. So you can't just equip a bunch of stuff that grants bonuses.
TL;DR: I definitely prefer bounded systems, but there's no reason an ascending system can't be bounded, as 5e demonstrates.
I dispute your logic Sir! The entire premise of your argument is "3e ascending AC had no upper limit, therefore ascending AC is inherently worse". My swords and wizardry white box game uses ascending AC and still retains the same range of possible AC's (S&W products list both AC calculations). Your argument is based on flawed logic. Descending AC isn't better because of limited ranges in possible values because those same limits can be applied to ascending AC (just not in the 3rd edition or later versions of it that apply continuous skill increases).
ReplyDeleteActually, now that I think about it S&W white box only goes from 9[10] TO 0[19], not all the way to -10[29]. Which is even a smaller range. Therefore S&W's flex AC/AAC is even better as it has a smaller chart! (Also, in case it needs to be said, I honestly don't care if people prefer ascending or descending AC. I'm just a nerd who loves arguing about unimportant nerd shit)
DeleteAs a minor nitpick, descending armor class prior to 3E was not at all unified. The details worked slightly differently in AD&D, B/X, BECMI. For example, 0e/BX go from 9 to -10, while AD&D adds 10, and BECMI uncaps AC and has enemies with AC values like -30.
ReplyDeleteI don't really think ascending vs descending really matters. Ascending is a bit cleaner for things armor "bonuses" etc, so i play with it even when playing ancient games like 0e or B/X, but the modern "groupthink" about negative being bad is by people who have never tried it. They both work easily and fine.