Tuesday, February 3, 2015

A 5e-Inspired Weapon vs AC Table

I have a quixotic obsession with Weapon vs. AC Tables. It is quixotic because at its core, D&D combat is extremely abstract. Once one starts to add things to make it more concrete (like a Weapon vs. AC Table), combat becomes complex, game flow slows down and becomes something I would rather not play anymore. When it comes to crunchy systems that simulate one-on-one or skirmish level combat there are far better games than D&D; however, it’s the abstract nature of D&D combat that gives D&D (especially in its older incarnations) much of its charm.

There is enough drama involved in the combat system that it is fun to play, but at the same time it is simple enough to get through a single combat quickly so that players can focus on whatever aspect of the game they are interested in, whether that be exploring, interacting with NPCs or hacking through as many monsters over the course of evening as possible.

I did, however, play war-games before I played RPGs. Therefore, part of my gamer-make-up likes the kinds of tactical choices one must make while playing a war-game. Thus, I have a deep-seeded desire to bring this kind of choice into the combat system of the RPG I play most often. Inevitably, though, the moment I polish off my latest and greatest Weapon vs. AC Table, reality sets in and I am faced with the fact that once implemented, I don’t want to play anymore.

Enter 5e and the Advantage/Disadvantage mechanic. This affords me the opportunity to make a Weapon vs. AC Table as abstract as feasible, thus keeping combat in the abstract rather than the concrete. This holds the possibility of tacking on a tactical choice for players simple enough that combat remains abstract and therefore something I might still want to play.

Since the Advantage/Disadvantage mechanic is a three tier system, both weapons and armor need to be characterized by three general categories. Weapons are quite straight forward:

  • Slashing
  • Piercing
  • Bashing

Armor is a bit more complicated; however, modern versions of the game do give us three general categories:

  • Light
  • Medium
  • Heavy

Thus we can assign the Advantage/Disadvantage mechanic as follows:

  • Slashing: Advantage to hit Light Armor; Disadvantage to hit Medium Armor
  • Piercing: Advantage to hit Medium Armor; Disadvantage to hit Heavy Armor
  • Bashing: Advantage to hit Heavy Armor; Disadvantage to hit Light Armor

One could also rule that unarmed combat automatically is at a Disadvantage against all armor types (unless one were a specialized class like the monk).

The biggest problem with this system is assigning an armor type to monsters. Rather than base it on AC, I would suggest using Movement as a general guideline:

  • 60’ = Heavy
  • 90’ = Medium
  • 120’+ = Light

This works reasonably well for most monsters. While there are anomalies, these are few and quite easy to adjudicate on the fly. For example, Giant Beetles have a Movement of 120’+. One can simply rule that all giant insects or creatures with exoskeletons have heavy armor. Goblins and halflings have a Movement of 60’ due to their size. It is easy enough to rule that they have Medium or Light armor.

Finally, as a general rule, PCs should be at a disadvantage against gigantic creatures like dragons, giants and purple worms regardless of what weapon type they use. This makes combat with such monsters epic in scale, something that I imagine such combats ought to be.


  1. I've been thinking along these lines as well and while I agree that it can hurt the abstract nature of combat, I've been pondering applying the Advantage/Disadvantage mechanic to Damage Rolls instead of the Attack Roll. A weapon "type" versus armor "type" chart can somewhat enforce the idea of Armor being Ablative rather than Passive defense (without resulting in the issues encountered with things like DR).

    1. To a certain degree, I have already used this mechanic with damage. T-H weapons in my Lost Colonies Campaign allowed players to roll two damage dice and take the higher of the two. The results were minimal enough that only one player regularly used T-H weapons.

      Plus, the abstraction of D&D combat isn't really whether a weapon hits or not, but rather whether or not it does damage. Thus, I would prefer using the Adv/Disadv mechanic with "to hit" rolls.

    2. I also like 2d take high for 2-handed weapons. I like using this to balance out the benefit of taking a shield or two weapon fighting. Don't know if it's enough to make up for the “strike last” thing that exists in some editions though.

      I agree that the abstraction is really the key here. I'm definitely a proponent of re-contextualizing the "to Hit" roll as just representing the chance that the opportunity to deal damage presented itself during the player's action, rather than directly applying loaded terms like “hit” or “miss.” Especially with longer rounds in D&D type games, the "single swing" thing never worked for me, although it does still persist with Ranged Weapons to a degree, due to ammo being a resource and “Missing” with a Ranged Weapon being less of a strain on the suspension of disbelief. A series of strikes, feints, parries, all get folded into that one roll to represent the six-ish seconds of fighting. Blows are exchanged, and contact is made with the foe, but that's all in the narration, informed by the results of the “to-hit” roll.

      I do worry a little bit about the effect in play for Adv/Disadv on "to hit" rolls. It seems like this has the potential to insinuate itself into most rolls, whereas with applying it to damage just applies to the "successful" rolls. If we're trying to model “the right tool for the job” then I don't doubt this will still work toward having the desired effect, but I'm still ruminating on the repercussions at a meta-level.

      To look at it another way: The to-hit roll (even with obfuscating AC, etc) telegraphs a degree success up front, and seeing a high roll eclipsed due to Disadvantage seems a little more de-protagonizing than having take-low with damage (a rolled “opportunity” is turned into a “failure”, with the damage rolls, some damage is still dealt).

      For non-5e games, where Adv/Disadv doesn't key into class abilities or other tactical choices, I still think this would be fine (the weird stacking doesn't come into play), and the results are similar: Fighters carry around multiple Weapon types, and try to be prepared for all Armor Type eventualities. This I like :)

      What I'm not sure about is if these “hits” and “misses” (if you'll forgive the misnomers :)) will occur with a different perceived frequency. Will the player see failure or “missed opportunities” sooner and more often with Disadv on the front-end like this? Or will it all come out in the wash (with Advantage having the opposite, protagonizing, influence)?

      High damage being eclipsed by Low could be said to have a similar effect I suppose, although maybe not as much, as “success” has already been established, so it doesn't create a “failure,” just less damage dealt. Damage die are also less granular and “swingy” because bonuses tend to play a much bigger part of the overall, but I keep coming back to an interesting side-effect: you're not “revealing” the Advantage/Disadvantage up front with the “to-hit”, instead you're waiting until damage is dealt to cause the players to re-evaluate their tactics.

      Same results over time: Player's develop knowledge and skill and begin to address the problem, until it becomes a non-issue with the Swiss Army Knife Fighters that, in my opinion, we don't see enough of in old school play :)