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

[Sadras]

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)

Yes and no.
i.e. You are negotiating with a captain of a trading vessel to let you and your companions reside within the vacant suites available on the ship as opposed to bunking in the common room with the rest of the sailors. Unfortunately, the ducal cartographers who also booked passage for the voyage are requesting the suites for themselves.

Sure one can resolve this using magic & coin, on the other hand you can turn this into a skill challenge.

 

[Bumamgar]

Yes, however as a DM, be prepared to have your players ignore the time you spent coming up with a skill challenge and come up with their own, outside-the-box solution because their characters have a wide range of abilities that aren't specifically linked to combat. I'm not saying 'don't use skills', of course skills play a role. But having a planned out list of skills that apply (major vs minor, etc) tends to put the players in a straight jacket. In 4e it actually helped remind players that there was more to the game than the combat grid (but was horribly implemented). In prior editions and now 5e, it's much better IMHO to have NPCs goals and skills outlined and then let the player's creative application of skills, spells, background traits, characteristics, bonds and flaws resolve the situation.

 

[Quickleaf]

Yes, however as a DM, be prepared to have your players ignore the time you spent coming up with a skill challenge and come up with their own, outside-the-box solution because their characters have a wide range of abilities that aren't specifically linked to combat. I'm not saying 'don't use skills', of course skills play a role. But having a planned out list of skills that apply (major vs minor, etc) tends to put the players in a straight jacket. In 4e it actually helped remind players that there was more to the game than the combat grid (but was horribly implemented). In prior editions and now 5e, it's much better IMHO to have NPCs goals and skills outlined and then let the player's creative application of skills, spells, background traits, characteristics, bonds and flaws resolve the situation.

This was bad design in 4e and remains so in 5e. Skill challenges written later in 4e's development listed strategies as opposed to specific required skills. And many of the cool challenges designed by savvy fans eschewed listing specific skills.

Certainly Guidance can have a significant impact, or a certain spell can act as a success or two toward a skill challenge. But if you've got a "skill challenge" which can be solved with a single spell then either (a) it's a badly designed skill challenge, or (b) the challenge is inappropriate to the level of the PCs.

 

[Bumamgar]

That makes sense. Clearly you are using the term 'skill challenge' in a more generic sense of 'there's an obstacle or situation for the PCs to resolve' rather than in the strict sense of Skill Challenge as outlined in the 4e core rules. The way you describe it sounds exactly like how I've been building adventures for years

 

[pemerton]

Skill challenges made more sense in 4e where there weren't any 'non-encounter' abilities for characters.

Other than skills and rituals, you mean?

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?

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

<snip>

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.

4e is based around much higher chances of success than 2 in 5 (which is what Quickleaf indicated upthread: +2 bonus vs DC 15). Most of the checks in a skill challenge will be Medium, and a character who is proficient in a skill, or has a good stat, should succeed at a Medium check around 2/3 of the time. If the character is proficient and has a good stat that success rate may be closer to 9 in 10. And that's before factoring in items, power bonuses etc.

Also, once the number of success required gets beyond 6 before 3 failures, 4e (post-Essentials) has the somewhat ad hoc system of "advantages" - basically, ways to mitigate adverse odds by column-shifting DCs or undoing failures.

Here is the "7 before 3" maths for a success chance of 3 in 4, which is not a bad generalisation for the bare bones of 4e:

The chances of 7 successes in a row is 3^7 over 4^7. This = 2187 in 16384.

The chance of 7 successes and 1 failure is 3^7 * 1 [for the failure] * 7 [because there are 7 "slots" into which the failure might fall, before the final success], all over 4^8. Which equals 2187*7 = 15309 in 65536.

The chance of 7 successes and 2 failures is 3^7 * 1^2 [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 2187 * 1 * 28 = 61236 , all over 4^9 = 262144.

Adding all these together over a common denominator:

(2187*16 + 15309*4 + 61236)/262144

= (34922+ 61236 + 61236)/262144

= 157394/262144

which is just a tiny bit more than 60%.

In practice, in 4e, I think the chance tends to be higher because of advantages, the ability to gain bonuses that lift the chance above 3/4, etc.


To get a 3/4 success chance in 5e (ie succeed on a 6 or better on d20), assuming a typical bonus of around +2, is going to require DCs of 8. Even if DCs are 10, the chances of success for characters with a +2 bonus (ie succeed on 8 or better on d20) is going to drop markedly.

If we treat a chance of 13/20 as a 2/3 chance (because I'm not going to do maths that involves 13^7!), then we get the following:

The chances of 7 successes in a row is 2^7 over 3^7. This = 128 in 2187.

The chance of 7 successes and 1 failure is 2^7 * 1 [for the failure] * 7 [because there are 7 "slots" into which the failure might fall, before the final success], all over 3^8. Which equals 128*7 = 896 in 6561.

The chance of 7 successes and 2 failures is 2^7 * 1^2 [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 * 1 * 28 = 3584, all over 3^9 = 19683.

Adding all these together over a common denominator:

(128*9 + 896*3 + 3584)/19683

= (1152+ 2688+ 3584)/19683

= 7424/19683

which is between 37% and 38%.


I don't think that's very viable, myself. It also shows that, with these sorts of numbers, the presence or absence of Guidance will make a very big difference to success rates.

 

[pemerton]

as a DM, be prepared to have your players ignore the time you spent coming up with a skill challenge and come up with their own, outside-the-box solution because their characters have a wide range of abilities that aren't specifically linked to combat.

As do 4e PCs.

having a planned out list of skills that apply (major vs minor, etc) tends to put the players in a straight jacket.

This was bad design in 4e and remains so in 5e. Skill challenges written later in 4e's development listed strategies as opposed to specific required skills.

Clearly you are using the term 'skill challenge' in a more generic sense of 'there's an obstacle or situation for the PCs to resolve' rather than in the strict sense of Skill Challenge as outlined in the 4e core rules.

From the 4e core rules (DMG, p 73, 75):

When a player’s turn comes up in a skill challenge, let that player’s character use any skill the player wants. As long as the player or you can come up with a way to let this . . . skill play a part in the challenge, go for it. . . .

In skill challenges, players will come up with uses for skills that you didn’t expect to play a role. Try not to say no. . . . This encourages players to think about the challenge in more depth and engages more players by making more skills useful.

However, it’s particularly important to make sure these checks are grounded in actions that make sense in the adventure and the situation.​

Also from the 4e core rules (PHB, p 179), under the heading "Skill Challenges": "It’s up to you to think of ways you can use your skills to meet the challenges you face."

A GM making lists of skills in preparing for a skill challenge is like a GM making a list of tactics for a combat encounter, or NPC responses for a social encounter: it is preparing advance guidelines and ideas for adjudication. It is not prescribing how the encounter will, or must, unfold.

 

[Jer]

A GM making lists of skills in preparing for a skill challenge is like a GM making a list of tactics for a combat encounter, or NPC responses for a social encounter: it is preparing advance guidelines and ideas for adjudication. It is not prescribing how the encounter will, or must, unfold.

Yes - this is something that I think DMs with experience in either skill-based (vs. class based) or narrative RPGs grokked, but that wasn't communicated in the 4e rules as effectively as it could have been. Especially when the early examples of skill challenges that were given out in adventures were very much structured like "if the PC tries this skill, here's how it works" which too often read as "here are the things that the PCs can try and here's how they work".

You have to prepare for your PCs to do something that will short-circuit your skill challenge because the PCs are creative. If I have a skill challenge that I initially plan for as "5 successes before 3 failures" difficulty and the third PC comes up with a clever use of a ritual or a magic item or an ability that I hadn't considered that would solve the whole challenge then just let it work. Congratulations - my players are smart! Or if the player has a bit of backstory or a contact or other story element that they've come up with outside of the "rules" that would help them then again it works and they've met the challenge. Or maybe it gives them an automatic success. Or maybe it just gives them a bonus to their roll. Whatever fits with what they propose you go with.

(I love skill challenges but my god the initial rules were opaquely written. I'd had experience with other games where player-directed choices for multi-success skill checks were a thing, so I could figure out the intent but I didn't envy folks who hadn't ever played in or run a game like that before. Add to that the level-based sliding scales of DCs in 4e and the fact that the DCs by level numbers kept getting "errattad" - making it hard to get an intuitive handle on where DCs need to be set - and I can understand why some people cringe when they hear the words "skill challenge" no matter how much I enjoy using them myself.)

 

[Sadras]

But if you've got a "skill challenge" which can be solved with a single spell then either (a) it's a badly designed skill challenge, or (b) the challenge is inappropriate to the level of the PCs.

Well put.

Most of the checks in a skill challenge will be Medium, and a character who is proficient in a skill, or has a good stat, should succeed at a Medium check around 2/3 of the time. If the character is proficient and has a good stat that success rate may be closer to 9 in 10. And that's before factoring in items, power bonuses etc.

Didn't realise 2/3 success is the standard for medium tasks, I would have guessed closer to 50%, with 75% success rate for easy tasks and 25% success for difficult tasks.

To get a 3/4 success chance in 5e (ie succeed on a 6 or better on d20), assuming a typical bonus of around +2, is going to require DCs of 8. Even if DCs are 10, the chances of success for characters with a +2 bonus (ie succeed on 8 or better on d20) is going to drop markedly.

Appreciate all the number-crunching. As an aside 5e indicates 10 DC for easy tasks.

From the 4e core rules (DMG, p 73, 75):
When a player’s turn comes up in a skill challenge, let that player’s character use any skill the player wants. As long as the player or you can come up with a way to let this . . . skill play a part in the challenge, go for it. . . .

In skill challenges, players will come up with uses for skills that you didn’t expect to play a role. Try not to say no. . . . This encourages players to think about the challenge in more depth and engages more players by making more skills useful.

However, it’s particularly important to make sure these checks are grounded in actions that make sense in the adventure and the situation.

For the purpose of clarity, this could lead to shared narration (player and DM)?
i.e. The PC in his attempt to obtain undisputed trading rights for his guild, could discredit his opposition's (merchant from another guild) backstory (even though the DM has not provided such information). The player, in a skill challenge, selects without a set skill-assigned framework, for his character to use his History skill to reflect him remembering the scandal of his opposition to bring it to the fore in the middle of the trade negotiations. Essentially the player narrates a reasonable scandal and makes the roll, creating NPC backstory content for the DM and character to use.

Is this an allowable application of the skills within a skill challenge?

 

[pemerton]

Yes - this is something that I think DMs with experience in either skill-based (vs. class based) or narrative RPGs grokked, but that wasn't communicated in the 4e rules as effectively as it could have been.

<snip>

I love skill challenges but my god the initial rules were opaquely written. I'd had experience with other games where player-directed choices for multi-success skill checks were a thing, so I could figure out the intent but I didn't envy folks who hadn't ever played in or run a game like that before. Add to that the level-based sliding scales of DCs in 4e and the fact that the DCs by level numbers kept getting "errattad" - making it hard to get an intuitive handle on where DCs need to be set - and I can understand why some people cringe when they hear the words "skill challenge" no matter how much I enjoy using them myself.

I agree with all these points.

The passages I picked out in my post above are fairly clear taken in themselves, but they're somewhat buried among other cruft in the DMG. Plus there is no unified presentation, with the explanation straddling DMG and PHB.

Like you, I benefited from long experience with a skill-based game (in my case, Rolemaster) plus a fairly good understanding of "narrative" games (HeroWars/Quest, Maelstrom Storytelling, and later on Burning Wheel, Marvel Heroic etc).

The changing DCs were also an issue. I think the "advantages" system in Essentials is, essentially, an admission by WotC that the DC maths is too hard to get right in and of itself, so the GM (or players, depending how the table handles it) are given "advantages" to even out the bumps! But it was always clear to me from the outset (between my own maths plus stuff that was being posted on these boards) that for success chances to be decent overall, the success chances for individual checks had to be very high.

That is what seems to be a potential stumbling block for 5e, at least based on this thread so far.

Especially when the early examples of skill challenges that were given out in adventures were very much structured like "if the PC tries this skill, here's how it works" which too often read as "here are the things that the PCs can try and here's how they work".

Yes. The presentation of particular examples didn't mesh well with the general description of the procedures. There was another aspect to this failure of presentation, too, which I want to address below.

You have to prepare for your PCs to do something that will short-circuit your skill challenge because the PCs are creative.

<snip>

Or maybe it gives them an automatic success. Or maybe it just gives them a bonus to their roll. Whatever fits with what they propose you go with.

My general preference is for auto-successes or bonuses. This relates back to my post upthread, about process vs pacing approaches to resolution. I see skill challenges as playing an important pacing function, and so rather than short-circuiting I prefer to introduce new sources of adversity/conflict, to keep the challenge alive.

But this is another flaw in presentation. WotC itself gives examples of play in which skill challenges are adjudicated on a pacing/meta-game rather than process basis - eg in Essentials the skill challenge ends when some thugs who were scared off earlier in the challenge (successful Intimidation) turn up again and stop the party's investigation (overall failure). This is a metagamed resolution: there is no ingame process connecting the final failure to the thugs. Rather, the challenge has failed and so the GM needs to create a reason, within the fiction, for that failure, and does so by bringing the thugs back onto the stage.

But nowhere does the book actually talk about this: what the GM has done, and why, and how a GM might do something similar in other contexts. (For me, a really stark contrast exists between this woefully inadequate approach and the cleverness and detail of Luke Crane's discussion of narrating failures in the BW rulebook and Adventure Burner.)

Especially for the introductory RPG, D&D has a history of terrible GM advice. (Moldvay Basic is just about the only exception, I think. I know a lot of people like the 4e DMGs, especially DMG 2, but that only drives home how poor the other D&D entries in the field are! Because the DMG 2 is nothing particularly special compared to BW, Laws' advice in HeroWars/Quest, etc.)

 

[pemerton]

Didn't realise 2/3 success is the standard for medium tasks, I would have guessed closer to 50%, with 75% success rate for easy tasks and 25% success for difficult tasks.

I'm working from the final, Essentials revisions to the DCs.

For Medium difficulty, these range from 12 (at 1st level) to 32 (at 30th level), or around 11 + 0.7 * level.

At 1st level, Proficiency is +5 (success on 7+) and a good stat is +3 to +5 (success on 7 to 9+).

At 30th level, a good stat is around +9, and the level bonus is +15, for success on 8+.

Hence an average success rate of around 2/3 (EDIT: for individual skill checks - skill challenges will have a noticeably lower success rate unless the PCs have better bonuses eg prof + stat, items, powers etc). This is pretty consistent across 4e: the notional success rate for attacks (based on the attack and defence numbers per level, for monsters and traps) is 3 in 5 (ie hit on a 9+).

For the purpose of clarity, this could lead to shared narration (player and DM)?
i.e. The PC in his attempt to obtain undisputed trading rights for his guild, could discredit his opposition's (merchant from another guild) backstory (even though the DM has not provided such information). The player, in a skill challenge, selects without a set skill-assigned framework, for his character to use his History skill to reflect him remembering the scandal of his opposition to bring it to the fore in the middle of the trade negotiations. Essentially the player narrates a reasonable scandal and makes the roll, creating NPC backstory content for the DM and character to use.

Is this an allowable application of the skills within a skill challenge?

I think this is a table-by-table issue. I certainly think it's open, and that sort of thing comes up in my game from time to time, but I know that others prefer stronger GM authority over backstory.

Something that I would think is less contentius in your example would be to make a Streetwise check to collect scuttlebut to discredit the merchant in question. I think the rules clearly intend to permit that, even if it didn't occur to the GM in advance, and so a bit of GM improvisation is required to handle the details of the resolution.