## Friday, April 11, 2008

### Please Stop Me Before I Broil My Brain Basket

Warning: Math Ahead

At the risk of appearing to be an anal-retentive, rules tinkering, tee-totaling geek, I’m going to dissect the ‘fine as is’ OD&D combat system. Why? Because I don’t find it fine as is, and I’m the kind of anal-retentive, rules tinkering, tee-totaling geek that’s not afraid to be called such.

Solstice disposes of attack matrices by using a basic attack score (Fighting Capability, or FC), measuring combat prowess by class and level, and adding this score to the d20 roll.

Very un-old school, but hardly new school. Just a simpler method of determining the result of a d20 roll to hit. Simple and elegant. Now, how easy this formula is depends upon how your brain is wired. To some, this is complicated, to others, it’s logical, and simple.

In order to implement this system, I had to define what each class’s FC was based on the OD&D Alternative Combat System, Vol. I, p. 19. This is the first ever D&D Attack Matrix, those little tables that became cumbersome and needless in AD&D. Needless as long as one was willing to use one of the alternative mathematical formulae back in the day.

FC is hard wired into the Attack Matrix, this formula just extracts that core value and implements it without a table. Once you understand the formula used to construct this, and all other D&D attack tables, you can more readily implement such formulae. Using the AC 2 row as an example, a Level 1-3 Fighting Man has an FC of 1. How do we know this? It’s simple if we know that we are using a 20 number combat model. The table shows a 17 is required to hit AC 2. 17+2+1=20. 17 being the roll needed, 2 being the AC targeted and 1 being that magic number (FC) that turns a 17 into a hit vs. AC 2 by totaling the formula to 20.

This gives us one method of determining hits or misses. The above formula requires that the player know the AC of the target, though, in order to solve the formula himself.

Here’s the one used in Solstice. 20 minus (roll to hit plus FC) = the AC that is hit. The player can easily declare he has hit AC X based on exactly one magic number, his FC. Knowing these formulae allows determination of the FC based on the information on Attack Matrix I. If you want to give the players a break, you as DM can do the final 20 minus step for them. Simple Elegance.

As presented in OD&D, FC equals the following values by class and level.

FM 1-3:1, 4-6:3, 7-9:6, 10-12:8, 13-15:10, 16+:13.

MU 1-5:1, 6-10:3, 11-15:6, 16+:8.

C 1-4:1, 5-8:3, 9-12:6, 13-16:8. Some DM’s might add 17+:10.

Now, to add another layer of house ruling, I adjusted the FC progression as presented on the matrix. I simply didn’t like the irregular progression of 1-3-6-8-10-13, nor did I like the fact that MU’s are as good as Clerics in melee at so many levels. So, I moved to a more straightforward approach for FM’s and Monsters of 1 HD (or level) equals 1 FC. MU’s start at FC 0, and gain one every three levels thereafter, up to FC 4 at level 13+. Clerics start at FC 1, and gain one every two levels, up to FC 8 at level 15+.

FM by level

MU 1-3:0, 4-6:1, 7-9:2, 10-12:3, 13+:4.

C level divided by 2 (round up). 1-2:1, 3-4:2, 5-6:3, etc

Seems easy enough, and reflects the fact that MU’s (in Solstice) have virtually no martial training, and are woeful in melee, while Clerics are militant holy-men, prone to smiting their foes with heavy, blunt objects. FM, and Monsters are the crème de la crème, as it should always be. A FM shouldn’t be penalized with a FC of 1 at level three, equal in melee to MU’s and Clerics alike, at least not in my opinion.

All of this being said, even disregarding my own tinkering with the FC of the classes as presented in OD&D, the Attack matrix as written can still be used with such formulae to provide a simple method of calculating the results of a d20 roll to hit.

Of course, this all depends upon how your brain is wired to begin with.

Whew, that’s a bit of over analysis which brings me to a few more points about armor, and OD&D, and another opportunity for over analysis. It seems that a lot of OD&D players and DM’s alike enjoy the simple, cardinal, static Armor Class rules. Armor Class in OD&D describes the actual armor a character wears, simple as that. Bonuses from magic or dexterity are subtracted from an attacker’s roll to hit, they don’t actually alter one’s AC. Sounds annoying to me, having to remember to tell the DM, who just rolled a monster’s to hit d20, and is cross referencing the score with the AC on a table, that he has to reduce the number rolled on the d20 by, say, 2. Hence we ended up in AD&D with a fluid AC, one that could actually change in value based on bonuses, and made this cross referencing easier, as there was no need to call out a number when you were being attacked.

Now, there are some truly fiddly ‘weapon type vs. AC’ tables out there (not in the LBB, thankfully) that list modifiers based on such scenarios. These tables make sense when using the OD&D AC approach, but are fiddly to the extreme in AD&D with fluid AC values. I don’t use them, never used them in AD&D, and won‘t use them in OD&D. That said, I can understand such a static AC system like the OD&D one having some minor use if you enjoy weapon type vs. AC tables. Those who enjoy such minutiae must struggle with exactly how a Unicorn found the Plate Mail and Shield it’s toting around, though.

Amongst the OD&D Grognards I am in the minority. Maybe it’s because magic modifiers are so rare and minor that it’s not a big deal to remember to subtract X from the attackers roll to hit. But why bother when you can simply add the bonuses to the AC itself? Well, for one, values under AC 2 aren’t on the Attack Matrix, and math is hard I suppose. Some prefer to think of AC as a code which instantly tells exactly what the character in question is wearing. In other words, there is only one way to get AC 4 in OD&D, wear Chain Mail and a Shield. I don’t need such information from an actual game play stand point, what I’d rather have is a number expressing how hard it is to hit said target. Besides, after playing D&D for a few decades, one knows what Chain and Shield is, I don’t need a character telling me they have AC 4. I think nearly everyone playing D&D knows that Chain and Shield is AC 4.

Fluid AC means less stuff to track, and FC means even more less stuff to track.

In Solstice, I really get my own fiddly going with Combat Rules. Logical pre game fiddly is good. In game fiddly is not.

If I wanted to get extra fiddly ala OD&D, I could leave AC as is, and introduce Attack and Defense scores. Once you separate AC out like this, it really boils down to Attack versus Defense scores, then adjust the d20 roll by that number, and refer to the Attack matrix. This is exactly what OD&D does. They just don’t call it Attack and Defense, in OD&D it’s the attacker’s bonuses adding to the d20 roll, and the defender’s bonuses subtracting from it. Hmmm. Seems like later editions really don’t stray too much from the OD&D combat model after all.

I’m thinking of an alternate, old school, new school hybridization based upon these mathematical truths. It uses 2d6 to hit, static AC (that old school enough for ya?), and Attack and Defense scores for the 3e in some of you. You hit what you roll, so the lower the better. That roll is modified by Defense minus Attack. If the modifier is negative, you have a better chance to hit, if it’s positive, a worse chance. Now the only task would be defining the FC’s based on a 2d6 model. Sounds easy peasy lemon squeezy. Ah well, another time for that one. It probably wouldn’t be as good in practice as it sounds, since the 2d6 bell curve is wrecked once you start dealing with modifiers.

I think I’ll go stick my head in the oven now. I’m about to throw all of this out and convert all AC’s to 20 minus AC. Just roll and try to hit it. I’d better stop now or I’ll follow the same progression that led to the oft maligned 3e rules.

~Sham, Delinquent DM

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## 2 comments:

Please continue with this line of thought. I in fact share your opinions on this matter, even though that means I get excluded from the True Grognard treehouse. So be it.

Thanks, James. IMO, extracting the FC in order to ease rolls to hit seems logical, even for 'true grognards', as should fluid AC, except in the case of 'weapon types vs. AC' table users (I don't know many of those).

The only thing Solstice does in this regard that might rankle a BtB player would be my restructuring of FC (by way of tinkering with the Attack Matrix). That's the only true 'house rule' in the post, the rest is just a simplified roll to hit formula using the OD&D rules.

Yeah, more on this later :-)

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