I must create a system, or be enslaved by another man's. I will not reason and compare: my business is to create.

- William Blake

Wednesday, February 09, 2022

Quick D&D/OSR thought: comparative rolls

Old school D&D uses few opposed rolls (with the exception of attack versus AC and damage versus HP). A spell saving throw, for example, requires the same roll if you're the target of a first-level elf or a 14th level magic-user. As I've noticed before:
But, basically, any roll in which the possibility of success relies on both your skill/power and your opponents' skill/power can be considered an opposed rolls. Which is very common today, but NOT usually the case with old school D&D. Saving throws, moving silently, hear noise, etc., were often used without any regard for the opposition's capabilities. Traditionally, there is no "contest" between move silently and hear noise, for example; these abilities are "self referential", relying solely on the character attempting them.

There are some opposed rolls in old school D&D, but they are often disguised and made complicated for no apparent reason. For example, giving the thief a 5% penalty to pick pocket for each level of the victim beyond level 5 is identical to just adding +1 per level on a d20 roll after level 5. Turn Undead is also a opposed roll between the cleric's level and the undead's HD.

The lesson here, I think, is that because D&D is a "class & level" game, opposed rolls should always take level into consideration. Used in this way, opposed rolls reinforce the "class and level" aspect of the game in a way that "rolling under ability score" does not.
Dispel magic is another good example. Some creatures work similarly (e.g., the phase spider, which I use as an example below, imposes a -4 penalty to poison save in the RC, unlike an "ordinary" giant spider).

This bothers me, since I happen to like opposed rolls. AND I enjoy aspects from both old school and contemporary D&D. So when I wrote Dark Fantasy Basic, I used opposed rolls, despite fearing it would make the game harder to use with OS/OSR modules.

I failed to see how to have both within the same system; either the roll is self-referential ("roll 12+ to save versus poison - any poison") or the difficulty is defined by your foe ("roll 12+ to resist giant spider poison, but you need 16+ if the spider is huge like Shelob the great"). 

And this changes the game fundamentally, since it affects the very essence of how saving throws work.

Maybe you already realized that I missed an obvious solution...

Size matters!

Here it is: use the old school method, but, as an optional rule, add the difference in HD to the roll.

Lets say you're a 3rd level fighter, and your poison save is 14. When facing a 2 HD snake, you get a +1 bonus, needing only 13 or more to succeed. But when facing a 8 HD phase spider, you get a -5 penalty.

If you're using target 20, this is even easier; just add your level to your roll and try to roll 20+, or , if using the optional rule, add TWICE your level to your roll and try to roll 20+monster HD.

Use this if you want high HD monsters and heroes to be significantly stronger against low-level creatures. Which I like; the 5e purple worm causing 3d6+9 damage plus 12d6 poison on a failed save seems more reasonable to me than 1d8 plus save versus death.

There are a few problems with this approach. It's too fiddly, and not strictly necessary; it requires one additional step; it makes the poison of a purple worm deadly 100% of the times against that 3rd level fighter (fighting a purple worms at level 3 is a bad idea anyway... and the same would happen in 5e); and we have to consider how to count PC's HD after level 9 (especially if you're going all the way to 36).

Also... I like how Dark Fantasy Basic turned out. 1d20+stat+skill, versus 1d20+HD, and that's it. Works well, and you could hardly make it simpler. Maybe I should do the opposite then: use the DFB method and leave the fixed target as an optional rule (say, roll 20+ to succeed against anything).

Anyway... its a start!

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  1. Personally, I am fine with being completely outclassed by certain abilities. As far as what to do after level 9, the reduced HP scaling can also be taken into account with only one bonus every 4 levels or so instead of every level. Kinda works out when you consider 1 HP to HD comparison. The math doesn't work consistently I know, so perhaps its +1 every 4 levels for 9 - 21 and +1 every 5 levels after that. You would then have a single bonus number for reference and roll. The 'fiddlyness' is handled outside of gameplay.

    1. Yes, something like that would be ideal. I think 2-3 levels could count as one extra HD; the HP would be similar, and you could collapse levels 10-36 into something like levels 10-20.