Let's Talk About THAC0

Lanefan · Jun 10, 2019

Beleriphon said:
As for the math, its very clearly: (Die roll + Modifiers) - THAC0 score = AC Hit

Thus, a roll of (13 + 2 for a magic weapon) - THAC0 18 = 3, so we hit AC of 3.

Even that's counterintuitive, as 15 - 18 = -3, not +3. You skipped mentioning the step that says 'reverse the +/- on the answer given by the formula to get the AC you'll hit'.

Either that, or you got it backwards and it should be [THAC0 - net roll result = AC hit].

Staffan · Jun 10, 2019

Back in the day, my players didn't have much problem with THAC0, but that was to a large degree because I had made a character sheet that had accommodations for it. I had one row for THAC0 that went something like this:

Base THAC0:____ Melee mod: _____ Melee THAC0: _____ Missile mod: _____ Missile THAC0: _____ Thrown THAC0: _____

Then I had a weapons table which had a column for Attack modifier (which would mainly be specialization and/or magic), and next to that a column for adjusted THAC0. When rolling, the player would calculate THAC0-(d20 + situational modifiers) and tell me the lowest AC they'd hit. At the time this seemed simple, but in retrospect that was just because of a lot of pre-calculations.

Yardiff · Jun 10, 2019

Combat is always easier when pre-calculations are done, doesnt matter which edition yor using.

lowkey13 · Jun 10, 2019

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Sacrosanct · Jun 10, 2019

There are two observations whenever we have discussions like that that always make me raise my eyebrows a bit.

1. The claim that THAC0 is too difficult, or that people have a difficult time figuring it out. Why? Because you're doing tougher math every time you take damage, or gain or spend your coinage treasure. If someone is having a tough time trying to figure out: THAC0-modified die roll, then certainly they have a hard time figuring out: current HP-modified damage taken or current gp - how much you spend. After all, with HP and gold, the numbers are often greater than less than 20 (which is the highest variance you'd typically find in THAC0, often much less).

2. The claim that when 3e came out, ascending was much easier. I mean, sure, on the surface ascending is more intuitive than descending, but 3e also brought with it a ton of extra modifiers, and huge numbers bloat, along with it. So in actual play, you did a lot more steps in 3e than in 2e. 3e not only had many more things that modified your rolls over 2e, but it also brought more complexity with things like 3 different ACs, and different attack bonuses depending on which attack you were making (2nd and subsequent attacks). So while ascending is more intuitive than descending, 3e compared to 2e was more complex.

billd91 · Jun 10, 2019

Sacrosanct said:
2. The claim that when 3e came out, ascending was much easier. I mean, sure, on the surface ascending is more intuitive than descending, but 3e also brought with it a ton of extra modifiers, and huge numbers bloat, along with it. So in actual play, you did a lot more steps in 3e than in 2e. 3e not only had many more things that modified your rolls over 2e, but it also brought more complexity with things like 3 different ACs, and different attack bonuses depending on which attack you were making (2nd and subsequent attacks). So while ascending is more intuitive than descending, 3e compared to 2e was more complex.

Whenever I read people comparing the complexity of the two editions (2nd and 3rd), I usually find how many people forget the complexity 2e had to offer. For example, there may have been multiple ACs in 3e, but there were caveats with AC in 2e as well. Did you use a shield? If so, your AC depended on facing and position as well as how many attacks were directed at you from the directions covered by the shield - so that's at least 3 ACs right there. Plus, there are times (and positions) where Dexterity adjustments do not apply. Ultimately, 3e isn't really more complex so much as it formalizes a few of the ACs so they're more obvious to the end users - the players. The lack of obviousness of the other ACs may have allowed individual tables to simply ignore them, but doing so didn't make the game as written less complex.

3e's iterative attack bonus may have been a little more complex, but it served as an alternative way to operationalize AD&D's half-step attack rates so players no longer needed to worry about whether not it was a round in which they got 2 attacks or just 1 with their 3/2 attack rate. It traded one complexity for another.

The one place 3e really is more complex is in the number of buffs that could apply. But with those, players could self-regulate. If they found tracking too many modifiers a drag, they were fully in control of how many they used.

And as far as tracking hit points complexity - there's a reason some players add up damage to compare with their max hit points rather than subtract damage from their current hit points. They get to trade the subtraction they find more difficult with the addition they find easier. And with the spending of gold? That's usually not in combat round time, so calculating that doesn't really hold up play time very much.

Gradine · Jun 10, 2019

To be brutally honest, the whole way BAB worked with multiple attacks/full attack action was probably one of the worst 3.X-isms.

Though still better than 3/2 attacks per round nonsense.

lowkey13 · Jun 10, 2019

*Deleted by user*

Beleriphon · Jun 11, 2019

Tony Vargas said:
Could they use it for a bonus to AC, before, too? Seems like Jedi do a lot of dodging and blocking.

A Jedi character could use abilities to boost rolls affecting their ability to block attacks with a lightsaber, or outright rebound blaster fire.

Beleriphon · Jun 11, 2019

Lanefan said:
Even that's counterintuitive, as 15 - 18 = -3, not +3. You skipped mentioning the step that says 'reverse the +/- on the answer given by the formula to get the AC you'll hit'.

Either that, or you got it backwards and it should be [THAC0 - net roll result = AC hit].

I totally did, which just goes to show that subtraction is not the way to go.