Saturday, January 30, 2010

Revisiting Weapon vs AC for Swords & Wizardry

One of the more infamous bits of D&D's history is the Weapon vs AC chart. As presented it is cumbersome to use and doesn't mesh well for monsters. Plus with the addition of new armor types in the transition from D&D to AD&D it can be argued it doesn't even represent what it was originally designed for. The fact that different weapons have varying effect against different armor.

Fortunately other RPGs have developed more elegant ways to simulate this effect. Most of them have one thing in common. They distinguish between three types of damage, a blunt mass, a edged blade, and with a point.

Using the ascending AC system of Swords & Wizardry

Chainmail is normally +5 to Armor Class
Looking at how the different damage type work the armor class probably look like this.

+4 vs Blunt - the chain mail spread out the impact of a blunt blow but it is flexible and doesn't offer much resistance.
+7 vs Edged weapons - this is where chain mail excels, blunting the impact of a edge across the wearer's flesh.
+3 vs Point attacks - chainmail doesn't do so well in this regard. Enough of an impact the links can be shoved apart, allowing the point to penetrate.

The above may be logical it is not practical for a D&D style game to have varying Armor Class. We can flip this around and turn it into modifier for a weapon attack.

The AC remains at +5. But for the attack his modifiers not look like this
+1 if attacking with a blunt weapon
-2 if attacking with a edged weapon
+2 if attacking with a pointed weapon.

Note that you will see in the armor chart that most armor offer superior protection against edged weapons. However remember using blunt and piercing weapons comes at a price of reduced damage. If you get past the armor with a hit your opponent is going to be hurt.

Here is the full armor writeup. The modifier are bonuses or minuses to the attacker's to hit roller.

Quilt +1 AC, -2 blunt

Soft Leather +1 AC

Hard Leather +2 AC, -1 Blunt, -1 Edge
The rigidity of boiled leather offer good protection against blunt weapons.

Ring +3 AC, +1 Blunt, -1 Edge, -2 Point
The metal rings on leather greatly improved protection against edged weapon. But it's flexibility makes it little better than soft leather, and no different for piercing weapons.

Scale +4 AC, +1 Blunt, -1 Edge, +1 Point
The scales increase armor protection overall especially against edged weapons, but it is flexible so while better than ring doesn't get the full benefit, and piercing weapons can slip in between scales with only the leather to stop it.

Mail +5 AC, +1 Blunt, -2 Edge, +2 Point
see above for comments

Banded +5 AC, +1 Blunt, -2 Edge
This represents various coats of plate, roman Lorica Segmentata, etc. Better than chain versus piercing weapons but more expensive.

Plate +6 AC, +1 Blunt, -3 Edge
Plate is the king of armor with superior protection to just about anything. Blunt weapons do the best as the broad impact allow the rigid metal to be bent more easily degrading the armor's ability to protect the wearer.

This is good for people centric campaign (like my own Majestic Wilderlands) but overly complex if you are dealing mostly with dungeons and monsters.

If using this system then for monsters treat their AC like soft leather with the Monster's AC equally effective against all weapons. If you think something is obvious (like a reptilian monster's scale) then by all means treat like one of the above armor.


Norman J. Harman Jr. said...

> it is not practical for a D&D style game to have varying Armor Class

Why do you say this?

I know an edition of D&D with three standard Armor Classes. Most (all?) vary if wielding shield. When various spells cast etc.

I can easily see asking "what's your AC vs Blunt" or "does slashing 16" hit. And it be less onerous than adding/subtracting every to-hit.

Robert Conley said...

Good point it can work either way.

Gothridge Manor said...

I think doing the weapon vs. AC subracts from the simplicity of the game. I can see it more for 1st ed retro clones, but for those games that clone themselves after the White Box to keep is as simple as possible.

DMWieg said...

I have been meaning to do something like this for some time now. Consider this very much stolen, sir. ;)

BlUsKrEEm said...

I really like this idea. This would be a great start for a Sword and Sandal setting, in the vein of "Ruins and Ronin."

Talysman said...

Nice compression of the Weapon vs. AC rules! I've been planning to write on this myself; your post will help me immensely.

You could combine this with the suggestions I made about materials for weapons and armor and have stuff like mail made of bone rings sewn to leather that acts like ring mail against bone or wood weapons, but with a -1 on all damage types vs. metal weapons.

Rusty said...

My group saw the problem with this back in the 70s with AD&D 1e, as most battles involved non-armored foes. I understand the reasoning involved, but I happier keeping everything pretty simple.

Tom Fitzgerald said...

As Rusty said the majority of battles are actually against monsters withour armour - thorough implementation of this system would require thinking through how blunt weapons effect oozes or piercing vs. dragons etc. Of course you could make similar ctagories or templates for monsters, hard scales, rubbery hide, thick fur, generally amorphous etc. but it would still be labour-intensive.

I think it would improve the dynamic in Man- vs. man combat, however and cause players to choose carefully, making combat more real.

Excellent post.

Tenkar said...

I'm generally of the "less is more" mindset, but with the right gaming group this could work.

S&W bends but doesn't break... heh