The cap of the THAC0 progression is a bit inconsistent

[suy]

I've been working on a tool that (among other things) happens to chart THAC0 progression vs XP. For simplicity reasons, I've been calculating the THAC0 progression manually instead of reading it through THAC0.2da, and I've noticed something that seems a bit inconsistent. I can't tell from P&P manuals if it's a bug or not (they don't mention *any* THAC0 cap in the PHB, they just put a pre-calculated table that stops at 20, but it also mentions using the progression above level 20), so I'm bringing it for discussion.

• Warriors (and Monks) stop improving at level 21, which makes sense given that they "cap" the base THAC0 at 0. Seems OK to me.
• Rogues (Thief/Bard) stop improving at level 21 as well, when they reach 10. Given that they progress at half the Warrior pace, makes some sense to me.
• All the rest (Mages, Sorcerers, Druids, Clerics...) seem to get the last improvement at level 22. That's a bit of a head scratcher for me. I don't know why that value. But capping at 22 it's the more common behavior, aside from the special case for Warriors.

Myself on the first try of the application that I've mentioned, started capping at either 0 THAC0 or level 22, but then realized that Thieves got one point of improvement over what happens on game.

I have no idea how I would proceed on this. But maybe I would just change the Rogues to be consistent with the other classes.

[jmerry]

Why that value? Because it's the first improvement after level 20 for priests and mages. They now get their 1/3 of a warrior's benefit, rounded up.

[suy]

OK, so I'm not sure if I got what you mean, but if I did, it would make some sense:

• Warriors progress from 20 to 0, so they improve 20.
• Rogues do so at half the pace, so they improve by 10, and cap at 10 (20-10=10).
• Priests do so at 2/3 and Wizards at 1/3, with the one third being ceiling(20/3.0)=7, hence they end at 6 and 13 respectively (20-14 and 20-7).

The key here is: why should it be rounded up? Or just rounded to the nearest integer, which yields the same value.

It doesn't feel wrong, but it doesn't feel entirely right either. Normally when explaining the rules the phrase "caps at level X" is used often, so I was looking for an explanation based on level.

[Trouveur80]

IMHO, it would be best to cap at 0 for all classes.

It doesn't matter much for wizards and their level 9 spells, but for rogues and priests it would mean keeping up powerwise with fighters and wizards, even in ToB.

[subtledoctor]

Interestingly, the PHB did not necessarily contemplate capping thac0 progression - after showing the table to level 20 it continues:

Quote

For a character higher than 20th level, find the Improvement Rate for the character's group in Table 54. There you'll find the number of levels a character must advance to reduce his THAC0 by 1 (or more) points. Calculate the character's THAC0 according to his level.

The caps in ToB/BG2EE seem to be a house rule adopted by Bioware specifically to balance play in the CRPG. 

(Haven’t looked at the PHB in a long time. It also says this: “More Than Just Hack-and-Slash - as important as fighting is to the AD&D game, it isn't the be-all and end-all of play. It's just one way for characters to deal with situations. If characters could do nothing but fight, the game would quickly get boring.” Sigh…)

Edited May 12, 2022 by subtledoctor

[kjeron]

4 hours ago, subtledoctor said:

For a character higher than 20th level, find the Improvement Rate for the character's group in Table 54. There you'll find the number of levels a character must advance to reduce his THAC0 by 1 (or more) points. Calculate the character's THAC0 according to his level.

But then it later lists "THAC0 limits" for each class group, with those limits being the same as their level 20 values (Wa:1, P:8, R:11, Wi:14).

And later still outright states, at least for Warriors: "Although their THAC0 ceases to improve once they reach level 20, ... (hits points and proficiencies) ...

9 hours ago, suy said:

OK, so I'm not sure if I got what you mean, but if I did, it would make some sense:

• Warriors progress from 20 to 0, so they improve 20.
• Rogues do so at half the pace, so they improve by 10, and cap at 10 (20-10=10).
• Priests do so at 2/3 and Wizards at 1/3, with the one third being ceiling(20/3.0)=7, hence they end at 6 and 13 respectively (20-14 and 20-7).

The key here is: why should it be rounded up? Or just rounded to the nearest integer, which yields the same value.

It doesn't feel wrong, but it doesn't feel entirely right either. Normally when explaining the rules the phrase "caps at level X" is used often, so I was looking for an explanation based on level.

There is no rounding.  Priests do not get [1 -> 0 -> 1], [1 -> 1 -> 0], or [0 -> 1 -> 1].  They get [2 -> 0 -> 0].

Warriors progress every level. Rogues progress every other/odd level. Priests progress every 3rd level (by 2). Wizards progress every 3rd level (by 1).

The Bioware devs gave every class their next would-be point of progression after level 20.  For Warriors and Rogues that is level 21, for Priests and Wizards it is level 22.

Edited May 12, 2022 by kjeron

[subtledoctor]

3 hours ago, kjeron said:

But then it later lists "THAC0 limits" for each class group, with those limits being the same as their level 20 values (Wa:1, P:8, R:11, Wi:14).

And later still outright states, at least for Warriors: "Although their THAC0 ceases to improve once they reach level 20

Huh. The version I was looking at does not contain those.

Possibly the early versions mentioned a limit, but by later printings in the mid/late 90s TSR was getting more comfortable with higher-level play. That’s when you started seeing stuff like Skills & Powers, Dragon Kings, etc. 

Edited May 12, 2022 by subtledoctor

[suy]

Same for me. I mentioned the PHB in the first post, and there is no cap that I found. Quite the opposite, it lists till level 20, but it says how to calculate beyond 20. I'm using the revised premium edition in PDF form. I can check the old manuals in paper, but only translated to Spanish.