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Message: <blockquote data-quote="Esker" data-source="post: 7893856" data-attributes="member: 6966824">I posted the hypothetical for the purposes of removing complexity and isolating one aspect of the comparison at a time. Discovering that you are fine with that hypothetical, where we've rescaled DCs and rolls, helps us narrow down the source of your discomfort, by ruling out the unequal spacing as a cause (since a d10 and a d100 have unequal spacing). It also confirms that you're comfortable using a confirmation die or similar mechanism to fill in the loss in distinctions between consecutive DCs created by unequal spacing (as I do when comparing ordinary 1d20 to 2*3d6-10).The only differences between that hypothetical and the original scenario (well, there are two original scenarios, differing by how much of a role you want luck to play, but let's focus on the 1d20 vs 2*3d6-10 one for now, since one of them is vanilla and thus hopefully has good intuition behind it, which should be easier than comparing two unfamiliar schemes to each other).In the 1d20 vs 2*3d6-10 case, we're rolling against the same DCs, so that removes yet one more point of complexity that we have to deal with in the 3d6 vs rescaled 1d20 scenario.Ok. So, with a regular 1d20, the distinct (adjusted) DC ranges are: [-infinity to 1], 2, 3, ..., 20, and [21 to infinity]. There are 21 functionally distinct DCs here. Anything with an adjusted DC less than 1 is functionally equivalent to an adjusted DC of 1, since there are no additional ways to succeed on, say, an adjusted DC of 0 that don't also succeed on an adjusted DC of 1.With 2*3d6-10, on its own, we have the following sets of DCs that can be distinguished: [-infinity to -4], {-3,-2}, {-1,0}, {1,2}, ..., {21,22}, {23,24}, {25,26}, [27 to infinity]. There are only 17 of these, and they don't line up with the ones in the 1d20 system. Because we can't roll odd numbers, -2 is no harder than -3, 0 is no harder than -1, etc. The confirmation mechanic breaks this up further (just as the confirmation mechanic in the d10 system in the hypothetical): since the confirmation mechanic only affects even DCs, we can now distinguish the following sets: [-infinity to -5], -4, -3, -2, -1, 0, 1, ..., 25, 26, [27 to infinity]. We've actually created more distinctions than we had with 1d20 -- a total of 33 -- because [-infinity, 1] is subdivided into seven different sets, as is [21 to infinity].Is this a problem? Well, it depends on your tolerance for approximation. In the 1d20 system, every DC from -infinity to 1 has the same difficulty, whereas in the 2*3d6-10 system, we get slight increases in difficulty when we go from -5 to -4, -4 to -3, from -3 to -2, etc., because we are losing ways to succeed: rolling a 3 on the 3d6 definitely succeeds if the DC is -5 or less, but only a 50% chance if the DC is -4, and 0% if it is -3. Rolling a 4 definitely succeeds if the DC is -3, but it only has a 50% chance of succeeding if it is -2, and a 0% chance if it is -1. And so on.There are two ways to look at the effects of this discrepancy. First, we can ask what happens if you have two characters facing a DC of 1, but one is rolling d20 and the other is rolling 2*3d6-10-(d2-1). The first character is guaranteed to succeed; they don't even need to roll. The second might fail, because they might roll a 5 or below on the 3d6 (corresponding to 0 or below after the transformation). This has a 4.6% chance of occurring. I'm not pretending this is nothing --- it's not, clearly, as it's only slightly less likely than rolling a 1 on the d20. But this is actually the worst the comparison ever gets. At DC 0 they still might fail (whereas the 1d20 character can't, obviously), by rolling a 3 or 4, or rolling a 5 and failing their confirmation roll. But this is less likely. And so on. The same thing happens on the other end of the spectrum, at those very high adjusted DCs.The other way you can look at the discrepancy is in terms of the value of a +1. If you have a character whose bonus puts them at an adjusted DC of 1 on a particular check, we can ask, what is the impact if that character gets an additional +1? Well, regardless of the roll mechanic, that +1 reduces their adjusted DC to 0. Now, if they're using a d20 that does nothing; they were already at 100% success. If using 2*3d6-10 though, it gives them a little bit of a boost: about a 1.4 percentage point increase in their success chance (i.e., the probability of both rolling a 5 and succeeding in confirming).Here, the graphs don't look nearly so similar, but the actual magnitudes of the discrepancies are still pretty small. The worst discrepancy in the value of a +1 is about 2.5 percentage points, which happens if you're currently sitting at a DC of 2: with 1d20 a +1 is always worth 5% within the range of 2 to 21 (because at each of these we add a new way to succeed), but at DC 2, a +1 is only worth about half that. The same at DC 21. Here are the graphs (since you didn't like the fact that I was interpolating between points before, I'm just plotting the points this time):<img src="https://imgur.com/P54UpyF.jpeg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" /><img src="https://imgur.com/X35arT3.jpeg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" /></blockquote>

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