Sunday, January 22, 2012

The Myth of THAC0

I read on another blog a few days ago (very new blog from 2012 - if you know it PLEASE let me know!) that BAB / BtH / THAC0 are all pretty much bullshit.  You aren't climbing a ladder when your character's chance to hit increases, because your level appropriate adversaries see a corresponding increase in Armor Class protection.  In effect, you are running up a down escalator.

The first game in the Dungeons & Dragons family that seem to recognize this was Castles & Crusades.  The combat bonus rate of increase for all classes with the exception of fighter based classes took a sizable hit from the D&D norm.  The cleric took the most noticeable hit his combat abilities from the D&D norm. I'm sure the main reason for this chance was to give the fighting classes a more noticeable niche of their own.  Still, it takes some of the importance off of AC / BtH.  As long as ACs don't increase at huge rate, there is less need to increase BtH and less need to pile on the magic items.

Raggi's Lamentations of the Flame Princess' Weird Fantasy RPG takes it a huge step further.  He totally removes any kind of combat skill advancement from all classes but the Fighter.  My initial reaction to this was a severe need and desire to house rule combat advancement back for the rest of the classes (and I probably would for Dwarves and Halfling, as they really have nothing going for them as it stands).  After taking a step back (and a few months away from my initial reaction) I realized this system works in the default setting of LotFP's Weird Fantasy RPG - 95% of your adversaries are normal men and such, fantastic creatures are unique and custom made and the world is magic poor.  Adversaries aren't going to be increasing in Armor Class all that greatly as the PCs level, and neither will the parties AC be changing all that much.  In some ways, the Fighter's niche of combat advancement is smaller then expected, as it is less valuable in a system that keeps Armor Class numbers within the realm of the non-fantasic.

It's an elegant solution to running up the down escalator.

I remember playing AD&D, back in my younger days, and if the party's front line wasn't in the negative numbers for AC by the time they were nearing name level, they were going to be hurting.  Just to maintain their place in the THAC0 / AC race, the need to dump magic armor and weapons an them was huge.  Such was the start of the Christmas Tree PCs  that were much the talk in 3e.  There are no Christmas Tree PCs in Weird Fantasy.

So, when your Fighter increases in his BAB in Swords & Wizardry, remember it's basically a wash.  Maybe not when fighting the mooks, but then they are books for a reason.  Your Fighter's increase in his to hit bonus has just been offset by a decrease in your level appropriate adversary's Armor Class.  Holy Shit!  Raggi was right! ;)

The more things change, the more they remain the same.


  1. I disagree. In the original/basic games, monster ACs range from 9 to 2. If there are any that go beyond that, it's certainly not the norm.

    What you describe certainly applies to 3E though.

  2. Not quite sure why this is a problem. It's a bit like telling a college physics major that their 4 years of study will just be running up a down escalator. After all, even though they learn more from semester to semester, the text books get correspondingly more and more difficult.

    The point is that as PCs advance in level, the creatures that were once really hard to hit become less so (just like to a 4th year physics student studying quantum, 1st year statics looks really easy), while the PCs themselves now stand a chance of hitting things that, at earlier levels, would have been unhittable (the spell checker is telling me that's not a word, oh well).

    Anyway, great blog, glad I found it.

  3. I would agree with your description of THAC0/etc. However, I think this could be said about every game. As characters advance, GMs must put in correspondingly advanced baddies. Be it with combat abilities, spells, feats, etc.
    The place where the real 'leveling' up happens in the story being ran. A long time ago I ran an AD&D campaign where the characters started as lowly adventurers that no one knew. As time went on and they had successful adventures people began to notice them and they were introduced to more politically powerful people until they ended up working for the local Duke. The level progression during this entire campaign? Three levels.

  4. The game takes this into account in several places, e.g. by having varying levels of difficulty on wilderness encounter charts. If the PCs know where the dragon lives from level one, they can fear him the entire campaign, but finally test themselves when they want to claim the barony for themselves at name level. A little foreshadowing goes a long way.

    If they encounter a raiding party of 30 orcs at 3rd level, they should probably hide and try and alert a garrison or something. At 9th level, they can just crush them outright. It feels very different.

    I noticed what you describe in 3.5 when our DM had every single set piece battle test us to the limit, every orc had class levels and items that threatened us. I feel like this is built into 4E, which is why it was fun for a few sessions but I can't imagine a campaign with it. (You're level 8 now, you get +1 to hit! Each monster's level and AC will go up by one, so your odds are the same.) The powers don't seem to change significantly enough to make it sustainable, to me.

    The 3E DMG suggests that 10% of encounters should be easy, and 15% more should be 'easy if handled right'. Combined that's 1/4 of encounters, which is more frequent than most DMs use, in my experience.

    The OSR really put this in perspective for me when I was introduced to Classic D&D and the progression to wilderness play, domain management, and henchmen. Each phase of the game is meant to feel different, not just in numbers, but in resources.

  5. This is really well put, and the scaling thing is something I try very hard to avoid. I like the fact that plate mail is plate mail is plate mail, and AC 2 should be a good AC no matter the level (IMO of course).

    I agree with Aplus, OD&D and B/X do not suffer from this problem. I do think it started to creep into AD&D to some degree, and definitely existed in Second Edition.

    I think this is also related to Zak's recent post about development through campaign play. If everything just scales, then you have a very similar game experience at level 1 as you do at level 20 (or whatever).


  6. There's another problem with the scaling - it over emphasizes the combat bonus one gets from strength. I might have another post on the subject later ;)

  7. I believe it's Steve Winter's new blog "Howling Tower" you're thinking of.

  8. fricking awesome! thank you anon! :)

  9. I think part of the "getting nowhere" feel you get with THACo comes from the artificial nature of encounters. Like Mike said above, high level characters should crush orcs under their heels, but it seems that in most games (and I'm just as guilty of this as the next guy) you stop running into orcs after you gain a few levels...or at least, you stop running into them in small numbers.

    Another way to look at it is like this... a 1st level fighter generally isn't capable of slaying a hill giant or a dragon. A higher level character might see the monster's AC and hit bonuses scale up, but that fighter is now taking on Major League monsters that 1st level fighters couldn't hope to best. When you go pro, everybody in the league is at a pro level of performance... but does that invalidate the achievement of going pro?

    Next time I run a campaign, I'll be more conscious about not having low level monsters/inferior opponents just kind of disappear as the party grows in power.

    Very thoughtful post. (As usual)

  10. @ryan - thanks. it was kicking around in the back of my head for a bit, but then a post here was the key:

  11. It isn't what you use, but how you use it. Remember that Dragon Mountain had the PCs go up against kobolds.


Tenkar's Tavern is supported by various affiliate programs, including Amazon, RPGNow,
and Humble Bundle as well as Patreon. Your patronage is appreciated and helps keep the
lights on and the taps flowing. Your Humble Bartender, Tenkar

Blogs of Inspiration & Erudition