Why Descending AC?

Descending Armor Class is a trope of BX, but as new retro clones appear, you also see THAC0 and Ascending Armor classes. Those are all choices, but which is best depends on who and when you are. And to be honest, which one you pick makes no difference. 

Way...way... way... back... to the DMG for AD&D, AC had a different mechanic than simply beating a number. There was a chart or series of charts that had endpoints. Characters reached a certain level where it was simply listed as "level n+". For Fighters, at the first level, you needed a 25 to hit AC -10 and an 11 to hit AC 10. Going to the other end, it didn't matter how high your level was; there was just one line labeled "This level or over". There were bounds to the charts. 

But if you ignore boundaries, all three attack systems are basically the same. 

For descending AC, you could fill out the Attack Value Matrix on your character sheet like so: 

Except this tool was in the hands of the DM! You would tell your DM what you rolled, and what your bonuses were. 

It would be up to the DM to consult the chart and tell you if you hit. What number you really need to succeed is obscured. This makes B/X and AD&D e1 especially deadly because you don't know what you don't know. Also, the tables had steps or jumps in probability not so much to keep one guessing, but due to the boundaries set by the charts and the progression of classes.   

For THAC0, instead of using the chart, you'd figure out what you need to hit AC 0, then calculate what you need to hit. In this case, roll a d20, subtract your opponent's AC, and see if it was better than what you needed. The two issues with this method are: first, the probabilities are different, and second, the monster's AC isn't obscured at all. 

You could either calculate on the fly all the time or fill out the Attack Value Matrix. It didn't matter, except as before, the tables were often not listed on your character sheet, and it still felt like the DM was slightly obscuring the needed info to calculate a hit. 

For Accending AC, you roll a d20, add your bonuses, and compare that number to your opponent's AC. This is different because this is all on the players, not the DM. A chart isn't necessary at all. 

So, why was Descending Armor Class ever a thing? 

A lot of people would answer: "Wargames have charts, and that is simply the way it was done". That's true, not the whole story. 

It comes down to how you were taught math and WHEN. For people coming of age in the 1960, you'd have a very different way of learning math. Check out this video. 

Believe it or not, the audio of this video is from 1965 as an objection to what was called "New Math". New math was what was taught from 1965 on. Math teaching changes. If you played D&D in the 1970s, you have experienced 4 changes in how math was taught. 

So, when Gary Gygax learned math, he didn't learn like the youngsters today. But he knew what he was talking about. 

Ask yourself, what is 3+4? Virtually every adult has this fact memorized, and no real math occurs. Even if you use your fingers. 

We'll call this the 7 configuration. 

Or does it? 

Ask a young child the same thing. 

Literally, 3 and 4. 

They will probably hold up 4 fingers on one hand and 3 on the other. There will be a pause while they put down one figure from the 3 hand and put up another finger on the group of 4 hand. 

And we are back to the 7 configuration.

Ok. They did some math right there, but what exactly did they do? Can you show your work, like the video jokes about? 

Yes, but you need to think in terms of spaces, not numbers or fingers. Theoretically, everyone has 10 fingers. 

 

Most of the time, I have 10 fingers.

OR we have 10 places to record things... numbers usually. But it could be pips, or apples, or oranges. 

Ok. So what is the point? 

We are back to the young child. The young child did some sleight of hand. First, he or she held up 4 fingers, then 3 fingers, then showed you all of them together. Next, he moved one figure from one hand to the other, to land in the seven configuration. If you live in a different country, which fingers you show would probably be culturally different, but still showing 7 fingers between two hands.

Now, let's show the work: 

10+4=14
10-3=7
14-7=7

Did I just do addition with subtraction?

Yup. 

That Trad Math, if you will. To add and subtract, you have a boundary - 10 fingers to hold information. If your range is between -10 to 10, you never need more than 10 fingers. 

Let's take slightly large numbers to prove it works, with more than 10 slots. Consider 47+38. 

100+47=147
100-38=62
147-62=85

Notice that for bigger numbers, I need the place above it. In this case, for numbers between 1-99, I need the 100's place. 

That is very different from putting 47 on top of 38 on the page, adding 8+7 for 15, adding 4+3 for seven, shifting the 7 to the left to represent the 10s place, and adding 70+15 to get 85. Watch that video again. Tom Lehrer found New Math totally perplexing. And it IS to some people. 

We are missing a step. In 1989, there were the NCTM Standards, which were different standards than New Math and also very different from the Common Core. The order is Traditional Math, New Math, NCTM Standards, and Common Core. All of which you would have lived with if you played D&D in the 1970s. 

This is why there was a progression from Descending Armor Class, to THAC0 and finally Ascending Armor Class. AD&D and BX are in the transition period between Traditional Math and New Math. 1989 marks the transition between New Math and the NCTM Standards. And Third Edition D&D and above marks the transition between the NCTM Standard and Common Core. 

Funny how that all works, with the dates lining up so neatly. 

So at my table, Traditional Math is king, with Descending AC. At your table, I bet it's something else, and you will have to thank your math teachers for making you just as right as me. 

Science Fiction - 000 Armor

This evening I read Population of Loss and was struck by the character Signalman.

He is a sort of mystical entity in a steampunk world. That is epic.

The image to left is a rendition of suit of armor from a reoccurring dream I used to have in the mid-1990s. While I believe my dream was trying to represent a version of me inside a high tech suit, all of my recollections of it are colored by a demented sort of dream-logic, which can seem a bit mystical.

Being from a dream, the suit does not have a name, but for the purpose of this post, I will call it the 000 Armor.

There are three tanks on this armor. The two tanks on the back of the armor contain a substance which is much colder than absolute zero. It shouldn't make sense, but mathematically, that substance should be hotter than hell while the area around it is intensely cold. To regulate that power, the small tank on the front contains an anti-matter reactor. It doesn't provide power to the suit, it keeps the irrationally cold meta-material in check. That work provides the power to the suit, mostly as an afterthought. The wearer's eyes are closed because he is frozen. Only his brain is working at incredible speeds due the cryogenic coursing through him.   

Being frozen, moving fingers are impossible, so the hands are protected by a pair of cestus-like weapons. The wearer cannot "see" light, but the suit is pouring in data from all across the em-spectrum. Moving in a traditional sense isn't really possible. The suit shambles like a zombie when it has to, but it's main motive power is provided by the super cold, meta-material. The suit possesses a property of non-locality. It simply shifts from one place to another. It can't sit idle, it tends to shift from place to place like the disruption of circular waves on a pond by a second rock. Seemingly random, but not really.

The suit's energy needs are met by the differential of temperature between it and the environment and this is moderated by the anti-matter reactor. Its meant for space but on the surface of a planet, it is barely balanced for basic operations. There is an area of alternating bands of temperature which has tendency of destroying everything around it. Plus, the suit is dumping hard radiation into the environment. Most things which come into close proximity to the 000 Armor are vaporized and rain down as an ash-like material over a vast area.

The suit takes moments to put on, but requires an incredible amount of technology to remove. The process takes weeks and is often fatal. While it can handle air, it has great difficultly when contacting solids, vapors and most especially, liquids. Falling in a body of water can drain the entire suit in short order, killing the occupant.

Should the suit start to fail, the operator can open their eyes. Ominously, the 000 Armor's heads up display will show a series of recordings, usually by loved ones, urging the user to fight to stay alive. You would think that this messages would be a digital and wholly fictional creation, but they are not. The operator is required to attend the recordings, so they understand that they must fight or die in these circumstances. 

The suit is tasked with fighting large robotic entities. Picture a city bus standing on its tail and mounted on top of very large tank in place of the turret. These robots have all manor of lasers, grenades, machine guns and missiles, which can wreck a city block or aircraft carrier in moments. It has 2 dozen missiles which are very peculiar in operation. They lay flat inside the main body and are forced out the top of the robot, at any angle. Picture a vertical launch tube on a submarine that can project a missile in any direction from straight up to completely flat. The robot has a small dead zone around it where the missiles cannot strike. Perhaps 40 meters around. The secondary weapons guard this area.

These weapons are all ineffective against the mobility that the suit provides.

The robot entity contains and carries a massive swarm of locust-like drones, which are supposed to collect data and repair damage. They also provide the motive force for the missile launchers.

It turns out that simply ramming the 000 Armor with drones is more effective than any of the robot's  weapons. In the image, you can see that the armor has been knocked around a bit by the drone swarm. The main reason is the swam can cover an area larger than the suit's non-locality function.

52 Weeks of Magic - 16 of 52 - Defender's Boss

The Defender's Boss is an unusual magic item. When found, it is approximately 4 inches around. It has an image of a lion painted on it and has a loop on the back as if it belongs on a chain or necklace. If worn in this fashion, it will improve the wear's AC by 1. If the wearer is a fighting type (ranger, paladin, cleric, etc.) who can normally use a shield, the Defender's Boss can be willed to grow to a maximum of 4 feet in size and it will act as a +1 shield. This is in addition the previous benefit of 1, for a total of two.

If the boss is used correctly and placed in the center of a shield, it will fuse to it and that shield will now be +3 and always magical. The shield will have the same ability to grow or shirnk as a the boss does.

If the shield is destroyed either by magic or a massive force, the Boss in entitled to it's own saving throw and if it succeeds, it will pop off the destroyed shield and be ready for use again in one day. If a smith or armorer attempts to remove it, it will respond to their desires and come off in their hands. No tools required nor will it lose it's powers.  

If this device is used by an assassin class character, it will not confer the bonus to AC for mere possession nor will it operate as a normal shield. When an assassin attempts to use it as a shield, it will grow to a full five feet in diameter forcing them to hold it with both hands or drop it. If held in this fashion, it will provide cover AND a +2 to AC. While recalcitrant to use by assassins, it will shrink or grow on command. 

If the boss is rammed into an opening smaller than it's diameter when fully deployed, the shield will squirm so that the boss is facing the character. If the shield is destroyed trying to expand, the boss will fall off the holder's hands. It does not want to be lost. Doing this will cause the item to lose it's magic for 7 days. 

If the lion symbol is painted over, any damage to the shield or boss will cause the paint to blow off, reveling the lion. 

Navigation

Week	Item	Week	Item	Week	Item	Week	Item
1	Magic Lamps	2	The Rat Bag	3	Emulous Cursed Sword	4	The Cloak of Peaceful Repose
5	The Cowl of Death	6	Scimitar of Smiting	7	The Symbol of Sol Invictus	8	The Equi Phalera
9	Libertatem	10	Sorrow	11	Aemilla Carna	12	The Obice Cardeam
13	The Gnollish Rattlebone	14	Bands of Roland	15	Shape of Memory	16	Defender's Boss
17	Missile Mirror	18	Stone Horse	19	Staff of Eyes	20	Helm of Aware Airs
21	Potion of the Lionhearted	22	The Unnamed Potion	23	Whispering Wings	24	Monk's Bane
25	Token of Infi	26	Coming Soon	27	Coming Soon	28	Coming Soon

Now, the commercial. I have a little book called Zero to Hero: Uncommon Commoners, over at DrivethruRPG. I am obviously thinking of writing another and Gnolls might be the subject. Please let me know what you think in the comments.