As a DM playing AD&D 2e how I worked out THAC0 was say the players THAC0 was 18 and the targets armor class was 4 just subtract 4 from the THAC0 and that was what they needed thier dice roll + bonuses to reach in this case a 14. If the target had a lower Armor Class say -2 you would add 2 to THAC0 so that would become a total of 20.
For the Player: Roll, add your bonuses. What is your difference from THAC0? THAC0 of 18. Rolls 12, adds the +1 and +2 for 15. 15 is 3 away from 18. You hit AC3 (or anything worse.)
Subtraction, like this, is the easiest way to calculate THAC0. You just tell the DM what AC you hit, they consult the AC and tell you if you hit or not. You can even make a "THAC0 Defense Chart" by writing -10 to 10 on one line, and on the line under that write your THAC0 under the 0 and add numbers up until you reach 10 and subtract down until you reach -10. Then all you have to do is look at your d20 role, consult the chart and tell the DM what you hit. (If you're playing with players that have a problem with subtraction.)
After years of hearing about how scary THAC0 was I am shocked at how easy to understand it is after watching this video. I think it's probably a mix of older games doing a really poor job with explanations, as well as newer generations of players having easy access to a treasure trove of really well produced videos like this one. Thanks for this!
I don't know about most of the people here, but I feel that the modern method is still better as the maths is still done for you. Monster has 15AC so roll 15 or higher to hit is more simple and intuitive means less work on everyone's part.
I think the idea is treating the game like a simulation. And they were trying to account for the inheritant difficulty of hitting something and how hard it was to do damage.
I actually liked the old ways, you were forced to use your brain, using more strategic choices had more benefit, now being lazy gives you the same benefit of someone who is actually trying to do their best in the game. Your brain is just like any other aspect of your body, if you don't use it, it atrophies... I tend to get more satisfaction out of a game where everyone is really trying than having someone who is relying on the rules to make it easy for them to succeed.
This method is pretty simple, but I have spent so many years doing it my way that any other approach would slow me down. Basically, I figure that I need to roll my THAC0 minus the enemy's AC (if it's positive) or plus their AC (if it's negative). So, with THAC0 18, if I am attacking AC 3, it's (18-3) 15+ to hit. If I am hitting AC-1, it's (18+1) 19+ to hit. When I started seeing AAC, I always found myself calculating it against THAC0 to see if it was "correct".
As someone who played and grew up on 1st, BECMI, BX THAC0 was never a problem. I don't hate 3.0 and later, just don't like all the added feats, skills, massive customization which just bogs down the whole game.
Isn't this just adding an additional, unnecessary operation? Doesn't it make more sense to just use ascending armor class, skipping the final addition or subtraction?
I really tried to like THAC0. The reason it went away is because it adds an otherwise unnecessary operation while also being less intuitive to learn or teach.
Can't you super simplify it as Thac0 - d20 roll = Armor Class hit? Like, if you have a Thac0 of 14, your target has AC 6, you need to roll 8 or higher.
I was appalled when they removed THAC0 in 5e, I mean it was a complicated thing and there are much easier ways of doing it and you needed tables to use it quickly, but it was THAC0! Players used to tell the DM 'I hit AC xxx', and that way the DM didn't have to do maths.
Nice effort, but even this is too complicated. Thac0 should be pre-calculated before you ever roll. If you have a natural Thac0 of 19 and a strength bonus of +1 and the sword is a +1 weapon, then the Thac0 for THAT weapon is 17, and you never have to worry about it until you go up in level. Then when you roll, you tell the DM what AC you hit. If there is a combat modifier the DM adjusts the AC to hit, the player needs ever to themselves. If you do Thac0 correctly it's barely math. No adding or subtraction, just noting the difference between your Thac0 and what you rolled on the die.
THAC0, was simple math. I have never understood the confusion. Take your PC's THAC0, let's say it's 15. You roll a D20 To Hit...let's say you roll a 15. What is the target's AC? 5? You add 5 to your roll...20. Target's AC is -2? You ADD -2 to your die roll...15 + (-2) = 13. Why is this so hard to comprehend? FTR...AD&D from 1978 used THAC0.
yo man, the portuguese version of the book says: "The player must subtract the target's AC from his THAC0" for example: my character has a THAC0 of 14, and I'm trying to hit an orc with a THAC0 of 6, so the math is 14 - 6= 8 to hit I've been using this since day one, why is it different?
It's the same thing, just different due to how the number is being applied. 14 THAC0 on 6AC would mean that you would either reduce from the number (as you did): 14-6=8 OR add 6 to your dice roll (say 10). The targets AC becomes an additive modifier (as explained in the video) giving you a plus to hit 0f +6 so the roll of 10+6=16 would be a hit on a THAC0 of 14
Bro its thac0, not thac0. Rhymes with hacko. Otherwise, thank you for this explanation. Its exactly how thac0 should be used. Players try reverse engineering monsters stats when all they need to do is what youve said. Theres always the chance of other hidden negative modifiers too, so people whining that thac0 is hard basically just suck at subtraction, and are probably metagamers lol
@@johnhiggins6602 I've never once (before this video) heard it call thEy-co instead of thAh-co. I get why you reason the "Aye" of AC, but it sounds weird 🤪😂
NOOOO! NOooooo. NOOO!!! You can't just explain THAC0 in 4 minutes!!!! It takes an advanced degree in Math to compute. I are a Smrt Nerd. Only smrt nerds play D&D. Yet somehow, I can't figure out addition and subtraction. NoooooooooooOOO-000000000000!!!!!
Thanks so much, just bought the OG Baldur's gate off humble bundle and I opened up my character sheet and was scratching my head. Thanks for explaining it so simply and precisly!
The key concept in Armor Class is the word "CLASS". In the Titanic, best rooms were "First Class", in a race, the best one is classified in the first position. So, the Best Armor possible, a First Class armor, is the Full plate armor, AC: 1 (or should we say AC 1st?) The less armor you have, the less you classify in the ranking of armors. A Chain Mail is in 5th position. A Studded Leather armor is in 7th position Having no armor is in 10th position. Any shield let's you go up 1 position in this classification. THAC0 is the "distance" of your hability to hit a Full Armor with a shield. Today's "Ascending Armor Class" is a wrong concept, they should have named it "Amount of Armor" (or, in order to keep the initials, I'd suggest "Amount of Covering" AC)
Yeah, it is almost as if designing a game around 17th/18th century British warship sizes would be clunky. Ascending armor classes just speeds up the game. Nobody has to convert 1st rate, aka AC-1 into AC18. There are tons of OSR games out there right now, essentially copycat games, most with the author's favorite house rules included. One of them (and I can't remember which one it was) was converting from ascending to descending and back is that it needs to add up to 19. If my old school AC is 3, and I want the modern target number style (ascending), then it is AC16. 3+16=19.
Yeah, that's a much better way of doing it than we used to by figuring out what AC we hit with our roll, which involved subtraction and all. However, as a GM, I really don't want to have to be doing the math for every freaking roll. To do that, the GM not only has to add the monster's AC, but also has to remember what the PC's THAC0 is. With ascending AC the player can simply roll and add modifiers and boom, that's what AC they hit. Player: "I hit AC 14." GM: "Nope, that's not a hit." GMs already have too much going on. I much prefer ascending AC and getting rid of THAC0. I've been running Basic Fantasy RPG for a group for a year and a half now and never want to go back to the old ways.
I played thousands of hours of AD&D 1e and 2e in the eighties and nineties not once did anyone add AC to rolls? This seems wrong to me, completely wrong. THAC0 means to hit armor class zero. The math was always simple enough we did to subtract AC from your character's THAC0 and that's your number to hit. Most often low-level characters THAC0 was 20, so if trying to hit an enemy with a 7 AC you have to roll a 13 after modifiers which sounds like a reasonable number for a low-level character to roll against that AC. If I had no modifiers for strength or a magic sword, simply rolling over a 7 AC would be ridiculously too easy.
Good explanation, I guess I understand it now. What a terrible system though, I can’t believe some people still play this way. Surely what people want is to have a swashbuckling fights with goblins and throw dice. Any system that adds time in between throwing dice and knowing if you hit, is not doing it’s job very well.
But this isn’t how it was used. The 2e DMG said “Figure strength and weapon modifiers, subtract the total from the base THAC0, and record this modified number for each weapon on the character sheet. Subtract the target's armor class from this modified THAC0 when determining the number needed to attack successfully.“ That's right: you were supposed to subtract a positive modifier from your THAC0 to get a new THAC0 for your weapon, then, during combat, add situational modifiers to the roll, and subtract AC from THAT. It's awful. What we actually did was add all the modifiers to the roll (because duh) & subtract the modified roll from 20, then announce the AC we could hit, which at least made the modifiers make sense. What they SHOULD have done was flip AC to be ascending, which is more intuitive, & turn THAC0 into an attack bonus (20 - THAC0). That allows you to just add it with your other bonuses to tell the DM the AC you could hit. That's what 3rd edition did.
I prefer the simple mantra "(adjusted) Die roll minus THAC0 = AC hit". That way the player is simply telling the DM what AC or worse they hit and it's a single comparison instead of the DM needing to do mental math for every attack roll.
Thac0 minus die roll equals armor class Hit number. ANY number rolled AT or Above the to hit number is a success- if AC is not known, if AC IS known 'Subtract AC from THAC0' to get hit number; negative AC is added to the Thac0 number; modifiers are added to the THAC0 according to Strength and weapon type; this is recorded on the character sheet; You determine your PC's Thac0 at the start of the round according to the weapon you are using or situational modifier to your Thac0 or your die roll- your DM will either tell you to Roll a die (hence the randomization element OR tell you an AC number to subtract from your modified Thac0; the caveat is that a 1 is ALWAYS a miss; and a 20 is always a Hit. You can still miss a roll no matter how powerful you are IF you roll a 1. There is such thing as fighting an enemy with 'You Roll a 1 or anything else you miss it- you must Roll a 20 to hit. (Any to Hit number going past 20 is agreed upon as the 1 or 20 decision to save time at some tables if you roll a 20 no matter the modifier needed to hit a number of 23 or beyond (most Dms avoid calculating negative AC's for NPC's unless the party had a habit of murder hoboing every NPC you came across once they reached a high enough level.) Rolling a 20 is always a hit, 1 is always a miss
It’s the player roll + modifier + enemy AC. In the example, the player rolls a 12, adds +1 strength modifier, adds another 2 magic sword modifier, then adds 6 for the stated enemies armor class.
So basicly you have a combat system where no matter how long it goes, players can't make it go faster because they can't just see their roll and say "I miss" or "I hit"
It baffles me that people find this baffling. I played DnD when I was 12 and descending AC was how I learned it. I think new players have just been conditioned to believe it is difficult.
The fastest, most intuitive and immediate method is, in my opinion, the following: 1) Record the base THAC0 for each weapon used on the character sheet; 2) Subtract from the base THAC0 all bonuses (Strength or Dexterity, magic bonuses, etc.) 3) Roll the d20 and subtract the result from the THAC0. You get the affected AC. Refer this value to the master who only needs to check the monster manual for the creature's AC. Example: 2nd level warrior with Strength 17 and magic sword +1: base THAC0 19, Strength bonus +1, sword bonus +1 --> total THAC0: 17 (remember that bonuses lower THAC0, so they must be subtracted from it) I roll a 16, so I hit AC 1 (17-16=1). the master checks the creature's AC and in a moment tells you whether or not the hit was successful. Alternatively, instead of subtracting the bonuses from the AC, you can add them to the die roll. Using the example above: I roll a 16, add +2 (Strength bonus and magic bonus) and get 18. In this case I subtract THAC0 from the roll: 18-17= 1. Personally, I prefer the first system, because once the THAC0 is written on the sheet I no longer have to remember to add the bonuses to the roll to hit. I just have to roll the d20 and subtract the result of the roll from the THAC0.
The fact that so many people struggle with THAC0 always made me worry about humanity. I played AD&D from 1988-2004 and never once, out of hundreds of players, have I actually seen someone not understand it. I really think either it’s a weird internet revisionism or I only ever played with super geniuses.
I don't know how it was ever confusing to people. But it sure was. Even way back in the day I remember people explaining it terribly. But for some reason everyone understands the modern system It's no different. In the new system, AC is your target number and everything else is a modifier. In the old system, thac0 is your target number and AC is just another modifier to your role. But even back in the day I remember people trying to explain it to me and reverse engineering the whole process to make AC the target number. That's not how it was supposed to work.
We always just stated AC hit based on dice roll against THAC0, the DM then anounced a hit or a miss. We didn't get too precious with the ins-and-outs of whether we could discern the monster AC during a battle. The purpose of THAC0 was to remove the need for the DM to reference combat matrices and placing the initial calculation of possible success on to the player instead of the DM.
Actually... many supplemental examples and rule explanations were provided in D&D subscription magazines (such as Dragon Magazine, White Dwarf, et cetera). We prefer THAC0 system as we carried it over from Gygax's Chainmail fantasy table top rules.
In AD&D each class had its own tohit table, I don't think they were all the same. I guess that means TSR simplified the combat system (and people had to buy a new DM screen 😜 which was probably part of the motivation)
Each class had its own THAC0 progression by level, and monster had theirs by hit dice. They had known for years that ascending AC would make everything simpler, but they didn’t want to break backward compatibility.
The original To hit system was extraordinarily convoluted since the "To Hit" number was actually only supposed to be known by the DM, was dependent upon character class and level, the type of weapon they were using, the type of armor the target may be wearing and the effective AC of said armor (a Battleaxe being used against someone in Scalemail, AC 6 vs someone wearing Chainmail, AC 5, actually gained a -1 to their to hit roll). The system was incredibly convoluted for a myriad of reasons, but I believe the biggest reason was primarily EGG trying to get out paying Dave Arneson royalties on OD&D by making the mechanics of the "To Hit" system a more table top style of mechanic (remember: TSR stands for Tactical Studies Rules). I don't recall what it was exactly that precipitated the fallout, but Arneson runing the Origins tournaments in the mid 70's really irked Gygax to no end. The history between Arneson and Gygax isn't really relevant to the topic except that AD&D was meant to appear legally distinctive from OD&D and Basic (BECMI). It should be noted that the THAC0 system was actually used on the DM's side nearly the entire time to ease the burden of refereeing, though the term was spelled out in the DMG for monsters in the back. And yes, it could also be said that EGG was just making things difficult in order publish more books for more money... I have a half closet full of books for 1E and 2E to prove it.
As a DM playing AD&D 2e how I worked out THAC0 was say the players THAC0 was 18 and the targets armor class was 4 just subtract 4 from the THAC0 and that was what they needed thier dice roll + bonuses to reach in this case a 14. If the target had a lower Armor Class say -2 you would add 2 to THAC0 so that would become a total of 20.
For the Player: Roll, add your bonuses. What is your difference from THAC0?
THAC0 of 18.
Rolls 12, adds the +1 and +2 for 15.
15 is 3 away from 18. You hit AC3 (or anything worse.)
Subtraction, like this, is the easiest way to calculate THAC0. You just tell the DM what AC you hit, they consult the AC and tell you if you hit or not. You can even make a "THAC0 Defense Chart" by writing -10 to 10 on one line, and on the line under that write your THAC0 under the 0 and add numbers up until you reach 10 and subtract down until you reach -10. Then all you have to do is look at your d20 role, consult the chart and tell the DM what you hit. (If you're playing with players that have a problem with subtraction.)
Ive never heard it explained before, and while i have questions, this makes total sense
After years of hearing about how scary THAC0 was I am shocked at how easy to understand it is after watching this video. I think it's probably a mix of older games doing a really poor job with explanations, as well as newer generations of players having easy access to a treasure trove of really well produced videos like this one. Thanks for this!
I don't know about most of the people here, but I feel that the modern method is still better as the maths is still done for you. Monster has 15AC so roll 15 or higher to hit is more simple and intuitive means less work on everyone's part.
Agreed we never use thaco
I think the idea is treating the game like a simulation. And they were trying to account for the inheritant difficulty of hitting something and how hard it was to do damage.
There needs to be a rule where people must read the wiki of a subject before posting a video.
I actually liked the old ways, you were forced to use your brain, using more strategic choices had more benefit, now being lazy gives you the same benefit of someone who is actually trying to do their best in the game. Your brain is just like any other aspect of your body, if you don't use it, it atrophies... I tend to get more satisfaction out of a game where everyone is really trying than having someone who is relying on the rules to make it easy for them to succeed.
Best and most simple explanation I have come across.
This method is pretty simple, but I have spent so many years doing it my way that any other approach would slow me down.
Basically, I figure that I need to roll my THAC0 minus the enemy's AC (if it's positive) or plus their AC (if it's negative).
So, with THAC0 18, if I am attacking AC 3, it's (18-3) 15+ to hit. If I am hitting AC-1, it's (18+1) 19+ to hit.
When I started seeing AAC, I always found myself calculating it against THAC0 to see if it was "correct".
Thanks for making this. Try and bump up the volume for future videos, but otherwise, masterfully done.
Best video I have ever seen on how to use THAC0
As someone who played and grew up on 1st, BECMI, BX THAC0 was never a problem. I don't hate 3.0 and later, just don't like all the added feats, skills, massive customization which just bogs down the whole game.
Isn't this just adding an additional, unnecessary operation?
Doesn't it make more sense to just use ascending armor class, skipping the final addition or subtraction?
I really tried to like THAC0.
The reason it went away is because it adds an otherwise unnecessary operation while also being less intuitive to learn or teach.
Can't you super simplify it as Thac0 - d20 roll = Armor Class hit?
Like, if you have a Thac0 of 14, your target has AC 6, you need to roll 8 or higher.
Perfectly explain. Great job. :)
I was appalled when they removed THAC0 in 5e, I mean it was a complicated thing and there are much easier ways of doing it and you needed tables to use it quickly, but it was THAC0! Players used to tell the DM 'I hit AC xxx', and that way the DM didn't have to do maths.
Nice effort, but even this is too complicated. Thac0 should be pre-calculated before you ever roll. If you have a natural Thac0 of 19 and a strength bonus of +1 and the sword is a +1 weapon, then the Thac0 for THAT weapon is 17, and you never have to worry about it until you go up in level. Then when you roll, you tell the DM what AC you hit. If there is a combat modifier the DM adjusts the AC to hit, the player needs ever to themselves. If you do Thac0 correctly it's barely math. No adding or subtraction, just noting the difference between your Thac0 and what you rolled on the die.
wow, mind blown, simply add AC to your roll. Thanks!
Is this mathematically different from hitting ac?
No.
THAC0 minus die roll equals armor class hit is superior.
Using this method, the players simply tell the DM what ac they hit.
THAC0, was simple math. I have never understood the confusion. Take your PC's THAC0, let's say it's 15. You roll a D20 To Hit...let's say you roll a 15. What is the target's AC? 5? You add 5 to your roll...20. Target's AC is -2? You ADD -2 to your die roll...15 + (-2) = 13. Why is this so hard to comprehend? FTR...AD&D from 1978 used THAC0.
THAC0, it rhymes with attack-oh.
yo man, the portuguese version of the book says:
"The player must subtract the target's AC from his THAC0"
for example:
my character has a THAC0 of 14, and I'm trying to hit an orc with a THAC0 of 6, so the math is 14 - 6= 8 to hit
I've been using this since day one, why is it different?
It's the same thing, just different due to how the number is being applied. 14 THAC0 on 6AC would mean that you would either reduce from the number (as you did): 14-6=8 OR add 6 to your dice roll (say 10). The targets AC becomes an additive modifier (as explained in the video) giving you a plus to hit 0f +6 so the roll of 10+6=16 would be a hit on a THAC0 of 14
I honestly like that THACO allowed for a greater range
Reminds me to take my ibuprofen.
Thanks, now that i finally understand it i can confidently say that i really do not like it
Bro its thac0, not thac0. Rhymes with hacko.
Otherwise, thank you for this explanation. Its exactly how thac0 should be used. Players try reverse engineering monsters stats when all they need to do is what youve said.
Theres always the chance of other hidden negative modifiers too, so people whining that thac0 is hard basically just suck at subtraction, and are probably metagamers lol
@@johnhiggins6602 I've never once (before this video) heard it call thEy-co instead of thAh-co.
I get why you reason the "Aye" of AC, but it sounds weird 🤪😂
@@hrayz TSR staff said "thay-co" for whatever that is worth.
NOOOO! NOooooo. NOOO!!! You can't just explain THAC0 in 4 minutes!!!! It takes an advanced degree in Math to compute. I are a Smrt Nerd. Only smrt nerds play D&D. Yet somehow, I can't figure out addition and subtraction. NoooooooooooOOO-000000000000!!!!!
Yeah this don't make no sense
Terrible explanation on the negative armor class
Thanks so much, just bought the OG Baldur's gate off humble bundle and I opened up my character sheet and was scratching my head. Thanks for explaining it so simply and precisly!
The key concept in Armor Class is the word "CLASS".
In the Titanic, best rooms were "First Class", in a race, the best one is classified in the first position.
So, the Best Armor possible, a First Class armor, is the Full plate armor, AC: 1 (or should we say AC 1st?)
The less armor you have, the less you classify in the ranking of armors.
A Chain Mail is in 5th position.
A Studded Leather armor is in 7th position
Having no armor is in 10th position.
Any shield let's you go up 1 position in this classification.
THAC0 is the "distance" of your hability to hit a Full Armor with a shield.
Today's "Ascending Armor Class" is a wrong concept, they should have named it "Amount of Armor"
(or, in order to keep the initials, I'd suggest "Amount of Covering" AC)
Yeah, it is almost as if designing a game around 17th/18th century British warship sizes would be clunky. Ascending armor classes just speeds up the game. Nobody has to convert 1st rate, aka AC-1 into AC18.
There are tons of OSR games out there right now, essentially copycat games, most with the author's favorite house rules included. One of them (and I can't remember which one it was) was converting from ascending to descending and back is that it needs to add up to 19. If my old school AC is 3, and I want the modern target number style (ascending), then it is AC16. 3+16=19.
@@weirdguy564 that might be Whitebox FMAG
Yeah, that's a much better way of doing it than we used to by figuring out what AC we hit with our roll, which involved subtraction and all. However, as a GM, I really don't want to have to be doing the math for every freaking roll. To do that, the GM not only has to add the monster's AC, but also has to remember what the PC's THAC0 is. With ascending AC the player can simply roll and add modifiers and boom, that's what AC they hit.
Player: "I hit AC 14."
GM: "Nope, that's not a hit."
GMs already have too much going on. I much prefer ascending AC and getting rid of THAC0. I've been running Basic Fantasy RPG for a group for a year and a half now and never want to go back to the old ways.
Exactly, less maths makes for faster game play.
I played thousands of hours of AD&D 1e and 2e in the eighties and nineties not once did anyone add AC to rolls? This seems wrong to me, completely wrong. THAC0 means to hit armor class zero. The math was always simple enough we did to subtract AC from your character's THAC0 and that's your number to hit. Most often low-level characters THAC0 was 20, so if trying to hit an enemy with a 7 AC you have to roll a 13 after modifiers which sounds like a reasonable number for a low-level character to roll against that AC. If I had no modifiers for strength or a magic sword, simply rolling over a 7 AC would be ridiculously too easy.
Good explanation, I guess I understand it now. What a terrible system though, I can’t believe some people still play this way.
Surely what people want is to have a swashbuckling fights with goblins and throw dice. Any system that adds time in between throwing dice and knowing if you hit, is not doing it’s job very well.
Yes, exactly that. That's how I've been explaining THAC0 to people for the last 30 years.
THACO forever!
But this isn’t how it was used. The 2e DMG said “Figure strength and weapon modifiers, subtract the total from the base THAC0, and record this modified number for each weapon on the character sheet. Subtract the target's armor class from this modified THAC0 when determining the number needed to attack successfully.“ That's right: you were supposed to subtract a positive modifier from your THAC0 to get a new THAC0 for your weapon, then, during combat, add situational modifiers to the roll, and subtract AC from THAT. It's awful.
What we actually did was add all the modifiers to the roll (because duh) & subtract the modified roll from 20, then announce the AC we could hit, which at least made the modifiers make sense.
What they SHOULD have done was flip AC to be ascending, which is more intuitive, & turn THAC0 into an attack bonus (20 - THAC0). That allows you to just add it with your other bonuses to tell the DM the AC you could hit. That's what 3rd edition did.
If you watch the video, I explain where the method I have described comes from.
I prefer the simple mantra "(adjusted) Die roll minus THAC0 = AC hit". That way the player is simply telling the DM what AC or worse they hit and it's a single comparison instead of the DM needing to do mental math for every attack roll.
Thac0 minus die roll equals armor class Hit number. ANY number rolled AT or Above the to hit number is a success- if AC is not known, if AC IS known 'Subtract AC from THAC0' to get hit number; negative AC is added to the Thac0 number; modifiers are added to the THAC0 according to Strength and weapon type; this is recorded on the character sheet; You determine your PC's Thac0 at the start of the round according to the weapon you are using or situational modifier to your Thac0 or your die roll- your DM will either tell you to Roll a die (hence the randomization element OR tell you an AC number to subtract from your modified Thac0; the caveat is that a 1 is ALWAYS a miss; and a 20 is always a Hit. You can still miss a roll no matter how powerful you are IF you roll a 1. There is such thing as fighting an enemy with 'You Roll a 1 or anything else you miss it- you must Roll a 20 to hit. (Any to Hit number going past 20 is agreed upon as the 1 or 20 decision to save time at some tables if you roll a 20 no matter the modifier needed to hit a number of 23 or beyond (most Dms avoid calculating negative AC's for NPC's unless the party had a habit of murder hoboing every NPC you came across once they reached a high enough level.) Rolling a 20 is always a hit, 1 is always a miss
Ok so I get what you explained that's simple enough, but where r u pulling the 18 from ?
It’s the player roll + modifier + enemy AC. In the example, the player rolls a 12, adds +1 strength modifier, adds another 2 magic sword modifier, then adds 6 for the stated enemies armor class.
So basicly you have a combat system where no matter how long it goes, players can't make it go faster because they can't just see their roll and say "I miss" or "I hit"
It baffles me that people find this baffling. I played DnD when I was 12 and descending AC was how I learned it. I think new players have just been conditioned to believe it is difficult.
When its set out as a question and there not a good worked example that gets people confused.
The fastest, most intuitive and immediate method is, in my opinion, the following:
1) Record the base THAC0 for each weapon used on the character sheet;
2) Subtract from the base THAC0 all bonuses (Strength or Dexterity, magic bonuses, etc.)
3) Roll the d20 and subtract the result from the THAC0. You get the affected AC. Refer this value to the master who only needs to check the monster manual for the creature's AC.
Example:
2nd level warrior with Strength 17 and magic sword +1:
base THAC0 19, Strength bonus +1, sword bonus +1 --> total THAC0: 17 (remember that bonuses lower THAC0, so they must be subtracted from it)
I roll a 16, so I hit AC 1 (17-16=1). the master checks the creature's AC and in a moment tells you whether or not the hit was successful.
Alternatively, instead of subtracting the bonuses from the AC, you can add them to the die roll. Using the example above:
I roll a 16, add +2 (Strength bonus and magic bonus) and get 18. In this case I subtract THAC0 from the roll: 18-17= 1.
Personally, I prefer the first system, because once the THAC0 is written on the sheet I no longer have to remember to add the bonuses to the roll to hit. I just have to roll the d20 and subtract the result of the roll from the THAC0.
The fact that so many people struggle with THAC0 always made me worry about humanity. I played AD&D from 1988-2004 and never once, out of hundreds of players, have I actually seen someone not understand it. I really think either it’s a weird internet revisionism or I only ever played with super geniuses.
I don't know how it was ever confusing to people. But it sure was. Even way back in the day I remember people explaining it terribly. But for some reason everyone understands the modern system
It's no different. In the new system, AC is your target number and everything else is a modifier. In the old system, thac0 is your target number and AC is just another modifier to your role.
But even back in the day I remember people trying to explain it to me and reverse engineering the whole process to make AC the target number. That's not how it was supposed to work.
We always just stated AC hit based on dice roll against THAC0, the DM then anounced a hit or a miss. We didn't get too precious with the ins-and-outs of whether we could discern the monster AC during a battle. The purpose of THAC0 was to remove the need for the DM to reference combat matrices and placing the initial calculation of possible success on to the player instead of the DM.
How I understand Thac0, add all modifiers and AC to the dice roll. If the total is 20 or higher, then you hit.
Is more easy that I was calculating it 😮
Agreed it is easy
I understood it at age 6
THAC0 is the WACO of d&d
We never used thaco in 30 yrs and after watching this..ill make sure we never use it
just read the PHB,
It's short and should be easy to understand. Will link to this one in case I need an explanation, so I won't have to do it myself. Thank you.
I think i love thaco even more now. Im not even gonna mention how i calculated it. But there's like 3 methods now.
It was brilliant! Why was not explained in that way in the books?
Actually... many supplemental examples and rule explanations were provided in D&D subscription magazines (such as Dragon Magazine, White Dwarf, et cetera). We prefer THAC0 system as we carried it over from Gygax's Chainmail fantasy table top rules.
@@DerSchleier I see, so it was Spanish editors' fault.
@@nosotrosloslobosestamosreg4115 Something is always lost in translation :(
Yes, he's saying it correctly....
Thanks Dave 🙂
Excellent video!
In AD&D each class had its own tohit table, I don't think they were all the same. I guess that means TSR simplified the combat system (and people had to buy a new DM screen 😜 which was probably part of the motivation)
Each class had its own THAC0 progression by level, and monster had theirs by hit dice. They had known for years that ascending AC would make everything simpler, but they didn’t want to break backward compatibility.
The original To hit system was extraordinarily convoluted since the "To Hit" number was actually only supposed to be known by the DM, was dependent upon character class and level, the type of weapon they were using, the type of armor the target may be wearing and the effective AC of said armor (a Battleaxe being used against someone in Scalemail, AC 6 vs someone wearing Chainmail, AC 5, actually gained a -1 to their to hit roll). The system was incredibly convoluted for a myriad of reasons, but I believe the biggest reason was primarily EGG trying to get out paying Dave Arneson royalties on OD&D by making the mechanics of the "To Hit" system a more table top style of mechanic (remember: TSR stands for Tactical Studies Rules). I don't recall what it was exactly that precipitated the fallout, but Arneson runing the Origins tournaments in the mid 70's really irked Gygax to no end.
The history between Arneson and Gygax isn't really relevant to the topic except that AD&D was meant to appear legally distinctive from OD&D and Basic (BECMI). It should be noted that the THAC0 system was actually used on the DM's side nearly the entire time to ease the burden of refereeing, though the term was spelled out in the DMG for monsters in the back.
And yes, it could also be said that EGG was just making things difficult in order publish more books for more money... I have a half closet full of books for 1E and 2E to prove it.
It's hard to listen to him mispronouncing the word that he's trying to explain.
Sorry about that MahdarOH.
Yup, painful! I was in the military and also very painful hearing movies adding "hours" after stating military time, drives me nuts!
Big whoop. He 'mispronounced' a made up nonsense word according to you.