Probability Math for Resistance (help!)

[sfedi]

Naive question:

Do you really have to take this into account?

Aren't Resistances almost always below minimum damage?

If that's true, then you can do the simpler: avg damage - resistance

OTOH, a quick and dirty simplification would be to have a minimum and maximum damage for each type of roll, and assume they have a uniform distribution.
That's much more easier to calculate.

I mean, you want to detect outliers, so a little aproximation will not harm the process. With care, of course.

 

[keterys]

I was doing it that way when I did a batch of 8 high level critters, but something like 3 or 4 of the 8 actually went negative. I mean 2d6+7-10 isn't much negative and I did that in my head, but 3d8+7 Halved - 10 was a little more complicated but still doable in my head, but I knew when I jumped up to resist 15 it would just be coming up over and over. Really I was _hoping_ I could have it as a formula so that you could just enter the resistances for your party and it would all autoupdate appropriately.

 

[sfedi]

Well, with the simple approach you will detect those extreme cases.

And AFAIK you don't want the exact average damage, do you?

 

[keterys]

There's no such thing as an _exact_ average damage on critters like this, no. So, sure, it won't be off more than 0-2 on the average for most creatures affected. Ie, 2d6-7's avg is only like .97 and 3d8-13 is 1.87

So that's a good reason to at least put in the option to specify resistances and have it give you the close enough results. Though, I mean, if there did exist an actual formula to just plunk in and someone knew it, I'd still rather that. But I've got two solid options, good enough.