Can someone explain Armor Class to me?

[DrDeath_MD]

For some reason I find this confusing. It seems like lower AC is better?

[Ithaqua]

In the original DnD, BECMI & ADnD (1&2) lower was better. With TETSNBN (3+) it was reversed.

Since this was ADnD (IIRC) it would be lower = better

[Emily]

When you make an attack roll, you're rolling to meet or beat your character's THAC0 score. The target's Armor Class is subtracted from that target number, e.g. an AC of 10 would subtract 10 from the target number to determine whether or not you hit, and an AC of -10 would add 10.

So if your THAC0 is 20, and your target's AC is 5, you need to roll a 15 (20 - 5) or better in order to hit. If your THAC0 is 2 and your target's AC is -12, you need to roll a 14 (2 - (-12)) or better.

[SAJ1573]

wat

[D'amarr from Darshiva]

In addition to the great PDF manuals for these games, there's a Wiki which explains a lot:

http://baldursgate.wikia.com/wiki/Armor_Class

[levelworm]

I believe there are also AC for different attacks, e.g. you see AC bonus for ranged attack / Slash damage / etc.

[Coldhands]

Originally posted by Aldrodamus666:

wat

That pretty much sums up a lot of AD&D. : p

[voehringer_nitron]

Originally posted by Aldrodamus666:

wat

You necroed a three year old thread to talk about Buddhist temples?

[Coldhands]

Originally posted by levelworm:

I believe there are also AC for different attacks, e.g. you see AC bonus for ranged attack / Slash damage / etc.

Yeah, most armors provide better or worse defense against bludgeoning, slashing, or piercing damage. It's all part of the way AD&D makes things needlessly complex in the name of extremely selective "realism." : p

[levelworm]

Originally posted by Coldhands:

Originally posted by levelworm:

I believe there are also AC for different attacks, e.g. you see AC bonus for ranged attack / Slash damage / etc.

Yeah, most armors provide better or worse defense against bludgeoning, slashing, or piercing damage. It's all part of the way AD&D makes things needlessly complex in the name of extremely selective "realism." : p

It's actually fine and fun when the computer controls the dices, I guess. In a real role-play session it's going to complicate things a lot...and then there is THAC0 and all kinds of modifications to AC and to-hit.

[jonnin]

AC 10 is supposed to be an average human (dex = 10) naked but able to move around.
AC 0 is a warrior in typical armor, strong metal maybe lightly enchanted. This is around the default for a new front line character who bought gear with starter money.
AC -10 was called "LO" and was as good as it got in pen / paper d&d. lo was used because -10 was hard to squeeze into the char sheet they provided. The super -20 etc stuff was later.

so you can see that it was originally fairly simple math. your to hit zero (thaco) - their ac = your roll or better to hit. So if their ac is 3, and your thaco is 10, you need 10 - 3 = 7 to hit. If their ac is -5, 10 - -5 is 15 to hit. Small numbers and simple math was the original concept here. The hit roll is a 20 sided die.

In hindsight this system was one of the biggest screw ups of old D&D. Turns out your average person can't actually do a subtraction in their head and becomes confused and frustrated by it.

[levelworm]

Originally posted by jonnin:

AC 10 is supposed to be an average human (dex = 10) naked but able to move around.
AC 0 is a warrior in typical armor, strong metal maybe lightly enchanted. This is around the default for a new front line character who bought gear with starter money.
AC -10 was called "LO" and was as good as it got in pen / paper d&d. lo was used because -10 was hard to squeeze into the char sheet they provided. The super -20 etc stuff was later.

so you can see that it was originally fairly simple math. your to hit zero (thaco) - their ac = your roll or better to hit. So if their ac is 3, and your thaco is 10, you need 10 - 3 = 7 to hit. If their ac is -5, 10 - -5 is 15 to hit. Small numbers and simple math was the original concept here. The hit roll is a 20 sided die.

In hindsight this system was one of the biggest screw ups of old D&D. Turns out your average person can't actually do a subtraction in their head and becomes confused and frustrated by it.

Probably even more confused after a few cups of ale...never played paper & pen ADND before and I'm just curious, how much of a typical module could be completed by a full-night (say 6pm-3am) session?

[captainwiseass]

Originally posted by voehringer_nitron:

Originally posted by Aldrodamus666:

wat

You necroed a three year old thread to talk about Buddhist temples?

*thumbs up*

[Juke Bredd]

Originally posted by jonnin:

AC 10 is supposed to be an average human (dex = 10) naked but able to move around.
AC 0 is a warrior in typical armor, strong metal maybe lightly enchanted. This is around the default for a new front line character who bought gear with starter money.
AC -10 was called "LO" and was as good as it got in pen / paper d&d. lo was used because -10 was hard to squeeze into the char sheet they provided. The super -20 etc stuff was later.

so you can see that it was originally fairly simple math. your to hit zero (thaco) - their ac = your roll or better to hit. So if their ac is 3, and your thaco is 10, you need 10 - 3 = 7 to hit. If their ac is -5, 10 - -5 is 15 to hit. Small numbers and simple math was the original concept here. The hit roll is a 20 sided die.

In hindsight this system was one of the biggest screw ups of old D&D. Turns out your average person can't actually do a subtraction in their head and becomes confused and frustrated by it.

Wow. Goes to show far D&D has come since then. That sounds super confuseing compre to 5E.

[danconnors]

That's because the average American never bothered to learn arithmetic in school. I've always believed ridiculing the THAC0 system just because the average American is too stupid to learn arithmetic is not very sensible. The average American is also too stupid to convert metric values to old English measures.

[levelworm]

Originally posted by danconnors:

That's because the average American never bothered to learn arithmetic in school. I've always believed ridiculing the THAC0 system just because the average American is too stupid to learn arithmetic is not very sensible. The average American is also too stupid to convert metric values to old English measures.

I think a few sessions of ADND games will dramatically improve the arithmetic ability.