D&D 5E Skill challenges in 5e - Math help!

[pemerton]

I don't really like the 4e skill challenge rules. It tries to create a rigid framework where none is necessary in my opinion.

the rigid structure only works well for certain types of challenges with clear goals, specifically ACTION challenges (what I'm emphasizing here), negotiations where the NPC has very specific set of demands/requirements to reach an accord, and planned investigations with specific clues. Maybe a few others, but those are the three I've had most success using the rigid structure with. I definitely would not apply it to exploration challenges or anything with a more free form structure

This seems to me to be a matter of playstyle preference.

Some people prefer process-oriented resolution: the rolls made to resolve a situation correlate, more-or-less, to the steps needed by the PCs to sort things out. For those who prefer that sort of approach, if the players declare an action that renders the situation resolved in a single roll, or with no need for rolls, the situation resolves itself.

The "rigid" framework of a skill challenge isn't meant to support this sort of resolution. It's mostly a pacing device: it keeps the scene alive until it has delivered the desired narrative impact. The results of checks, therefore, can include not just the processes deployed by the PCs, but external complications introduced by the GM as part of keeeping the scene alive.

It seems to me that hit point combat is more like the second sort of resolution approach - no matter how good a player's plan to decapitate the orc, or no matter how foolproof the player's description of his/her PC's feint and strike, the combat can't end until the hit points are all depleted. (I know some people treat hit-point combat in a proces-oriented way, but I don't really get that.) Crit-based resolution (RM, RQ etc) is more like the first approach.

Hopefully the "modular" DMG will talk about the rationale behind these various sorts of approaches to resolution, and give a range of options.

 

[Tony Vargas]

I notice my games tend to fall into some ratio of:

• Combat
• Exploration
• Interaction
• Action Challenge

In 5th edition, how would you design such a challenge (given my parameters)?

Nice. I suppose if every second counts and lives are on the line, it's pretty close to combat, but why quibble?

5e would handle this the same way it handles most things: players declare actions, DM describes result or calls for a roll first if the result is in doubt. Given time-importance, I might adapt the initiative system from combat. Physical dangers could attack, force saves, do damage, etc, you just don't generally have the option of fighting back against an avalanche or pool of acid (though you should be able to 'fight' a fire - hopefully not with fire)....

 

[Quickleaf]

[MENTION=42582]pemerton[/MENTION]
That's a good conversation to have, no doubt, and different groups will fall on different points of the process-abstraction spectrum, but I'm going to focus on applying the idea of skill challenges to 5th edition for the time being.

Disclaimer: It has been a while since I took a stats course in college, so my number will certainly need double-checking.

I'm going to assume some things because, well, you have to in order to get numbers to work with. Here are my list of assumptions:

• Average party size in 5e is four PCs, and they all contribute to any challenges they face.
• On most ability/skill checks ability modifiers at low levels (0-5) average out to +2.
• No special abilities or spells are used to increase ability checks or gain advantage.
• Ability/skill check DCs tend to average out to Medium (DC 15) in the long run.

So if I want to find out the odds of success in a skill challenge which requires, say, 7 successes before 3 failures, with a party of 1st level PCs, how would I do that?

I know that Multiplication of Probabilities applies and that average individual chance of success on a give check is 50%. But when it comes to figuring out how all this works compared to 3 failures, I'm a bit flummoxed. Any math wizards up for lending a helping hand?

 

[Supersonic159]

Oh this is a good idea, I'm going to try and incorporate some events like this into my current campaign!

 

[pemerton]

I'm going to assume some things because, well, you have to in order to get numbers to work with. Here are my list of assumptions:

• Average party size in 5e is four PCs, and they all contribute to any challenges they face.
• On most ability/skill checks ability modifiers at low levels (0-5) average out to +2.
• No special abilities or spells are used to increase ability checks or gain advantage.
• Ability/skill check DCs tend to average out to Medium (DC 15) in the long run.

So if I want to find out the odds of success in a skill challenge which requires, say, 7 successes before 3 failures, with a party of 1st level PCs, how would I do that?

Permutations and combinations. It's actually quite painful, at least by hand and using the resources of a high school maths students. (Those who have done higher study may have learned some shortcuts?)

Your chance of success, at +2 vs DC 15, is 2 in 5 (ie need a 13+ on d20).

The chances of 7 successes in a row is 2^7 over 78125, or 128 in 78125.

The chance of 7 successes and 1 failure is 2^7 * 3 [for the failure] * 7 [because there are 7 "slots" into which the failure might fall, before the final success], all over 5^8. Which equals 128*21 = 2688 in 390625.

The chance of 7 successes and 3 failures is 2^7 * 3^2 [for the 2 failures] * [the number of ways of allocating 2 "slots" out of 8 to failures, = 8!/6!2! = 8*7/2 = 28]. So 128 * 9 * 28 = 32256, all over 5^9 = 32256 in 1953125.

Adding all these together over a common denominator:

(128*25 + 2688*5 + 32256)/1953125

= (3200 + 13440 + 32256)/1953125

= 48896/1953125

= 0.025034752

That is, a little more than 1 in 40. That seems intuitively plausible, too, which gives me confidence in my maths.

 

[Savage Wombat]

I don't want WotC to try to port 4e skill challenges to 5e.

I want three or four of the people on ENWorld (and maybe other sites) who can conclusively say that they've gotten skill challenges to work consistently in their own games to write up a 5e port together. So that instead of game theory and corporate "playtesting" we get solid experience and deep understanding of the mechanic. Nothing that was typed up quickly to meet a deadline.

 

[Quickleaf]

That is, a little more than 1 in 40. That seems intuitively plausible, too, which gives me confidence in my maths.

Hmm. I knew the number was going to be low, but a 2.5% chance of a party of 4 PCs succeeding at a skill challenge requiring 7 successes before 3 failures is REALLY low!

Obviously, my assumptions are meant to produce a lower baseline, which would then be augmented by high ability scores, expertise, and other character features, but 1 out of 40 times you'd expect a party to succeed facing this sort of skill challenge in 5e? Ouch!

Unless I'm reading your math wrong?
[MENTION=1932]Savage Wombat[/MENTION]
I think that's what we're figuring out here

 

[nomotog]

Hmm. I knew the number was going to be low, but a 2.5% chance of a party of 4 PCs succeeding at a skill challenge requiring 7 successes before 3 failures is REALLY low!

Obviously, my assumptions are meant to produce a lower baseline, which would then be augmented by high ability scores, expertise, and other character features, but 1 out of 40 times you'd expect a party to succeed facing this sort of skill challenge in 5e? Ouch!

Unless I'm reading your math wrong?

@Savage Wombat
I think that's what we're figuring out here

It could get worse when you think about how your not guaranteed to be able to apply your proficiency bonus. You no longer have that guaranteed baseline you had in 4ed. It could get very sticky if you carry over the rules about failure and the rule that everyone has to participate.

 

[Sadras]

Hmm. I knew the number was going to be low, but a 2.5% chance of a party of 4 PCs succeeding at a skill challenge requiring 7 successes before 3 failures is REALLY low!

Obviously, my assumptions are meant to produce a lower baseline, which would then be augmented by high ability scores, expertise, and other character features, but 1 out of 40 times you'd expect a party to succeed facing this sort of skill challenge in 5e? Ouch!

That's definitely the lower baseline but not the middle ground which is what we should be looking at to be fair.
Like you have mentioned high ability scores, expertise dice and other character features also would play a roll, but what I think you might have forgotten is the action "Help" which provides advantage on the skill challenge (an extra d20 has definitely gotta come in handy )
I admit you cannot use the "Help" for all cases.

• May I ask in 4e would you use a skill challenge of 7 success before 3 failures with 1-3 level characters? Just asking, and I don't have the books in front of me and it has been a while.
• Also given that 4e promotes maximising abilities and 5e does not, perhaps the DC of 15 might be a little high initially for level 1-3 characters. In 5e levels 1-2 are really novice levels.
• +2 is really when there are no ability modifiers on the roll, given that someone would be proficient with the skill in order to get the +2 proficiency bonus, you'd imagine they would (some of the time) at least have a +1 modifier from their ability

Then there is the much debated about cantrip "Guidance" that's an additional +1d4 on skill checks.
This again, has practical limitations, as it can't be used in every skill challenge or for every check in a skill challenge.

Your results definitely reflect the worst case scenario - the same exercise should be worked with modifiers, advantage and such and then perhaps average it out between worst results and great results to be fair.

 

[Bumamgar]

Skill challenges made more sense in 4e where there weren't any 'non-encounter' abilities for characters. 5e has gone back to the prior editions in granting characters (primarily via spells, but also backgrounds and tool proficiency) with a much wider range of non-combat specific abilities. Skill challenges as a non-combat resolution mechanic simply don't make a lot of sense in a system where characters have access to actual spells (and not just grid-based combat abilities with an 'arcane' power source)