I know, I know. Addition is easier than substraction, what kind of backwards grognard do you have to be to like descending AC in 2024? I get all that. But hear me out for a moment. My argument is that whilst ascending AC may be marginally easier to calculate to begin with, descending AC offers something different - A more intuitive appreciation of what the numbers mean  and how they are bounded. AD&D Armors We'll start at the very beginning. Before that, even. An early draft for the first version of D&D: Target20  was basically the original conception. Deduct AC from 20 and you have your attack target roll. Which is of course also how one converts descending AC to ascending. One wonders why they didn't just include this explanation to begin with, alongside a +to hit modifier, instead if messing with THAC0. The math in the draft is a bit off, but it suggests another, even more intuitive, layer. If we stipulate that one must exceed the AC and not just meet it, it means t

There are three armor types in classic D&D (B/X, BECMI, Cyclopedia). Leather (AC7), Chain (AC5), Plate (AC3).  In terms of classes, fighters, elves, dwarves, halflings and clerics can use all armor, thieves only leather armor and magic-users no armor. This is important, because this frames why people wear the armor they do. Why would anyone wear leather armor? Because they can. That means thieves. Thieves can wear leather, magic-users can not and that gives thieves an advantage. It's also cheap and only weights half what chain weighs. There are no real downsides to wearing light armor over no armor, except weight. There is rarely much reason to wear chain armor though. Plate mail is only slightly heavier and pricier and any class able to wear chain can also wear plate. In other words, chain is almost never a meaningful choice. It's going to be all Clyde Caldwell for this entry. It's All AC5, baby. So maybe we should find some reasons to make the choice between chain and