D&D 5E Weak Saving Throws

[Ancalagon]

Advantage is at it's most beneficial when you have about 50% chance of success. If the save is weak, advantage won't help as much.

 

[FormerlyHemlock]

Advantage is at it's most beneficial when you have about 50% chance of success. If the save is weak, advantage won't help as much.

Depends how you measure "most helpful". For example, if you fail your saves only on a 1 (95% success), advantage cuts your failure rate by 95%. If you fail 50% of the time, it cuts your failure rate by only 50%. This is good for e.g. concentration. On the other hand, if you succeed only on a twenty, advantage doubles your success rate, which can e.g. halve the duration of enemy spells on you.

I'd argue that it's actually fallacious to interpret advantage/disadvantage as a linear bonus on a d20. Advantage isn't "equivalent" to +4 on your roll, nor is disadvantage equivalent to -4. Both of them are actually ways of transforming the probability distribution into something roughly bell-curved.

In 5E fights, it's usually more advantageous to impose disadvantage on an enemy than it is to gain advantage yourself. In fact, there are even cases (e.g. archery duels) where it can be a smart move to impose disadvantage on both parties, especially if you are higher on the bell curve than the enemy is or if you have extra rate-limited resources (monk missile catch 1/round). A barbarian can reduce the damage he takes in combat by up to about 50% via advantage from Reckless Attack; but a monk can reduce the damage he takes in an archery duel by far more than 50% by dropping prone.

 

[CapnZapp]

Depends how you measure "most helpful". For example, if you fail your saves only on a 1 (95% success), advantage cuts your failure rate by 95%. If you fail 50% of the time, it cuts your failure rate by only 50%. This is good for e.g. concentration. On the other hand, if you succeed only on a twenty, advantage doubles your success rate, which can e.g. halve the duration of enemy spells on you.

Stop stop stop.

Saying something like "if you fail your saves only on a 1 (95% success), advantage cuts your failure rate by 95%" does everybody a huge disservice, since you aren't normally interested in how much advantage specifically cuts your failure rate.

The pertinent number is: what is your probability sans advantage? what is your probability with advantage? Now subtract one from the other. This is the value of advantage you should be concerned about.

In your case, your success rate is 95% without advantage, you only fail on a 1. With advantage, 95% of those failed results are removed, but since rolling a 1 only happens 5% of the time, this is much less of a boon than you make it out to be. Your success rate increases to > 99% which means advantage only increases your success rate by close to 5 percentage units.

Or, in layman's words, when you only fail on a 1, advantage only provides a very small benefit. Which is the exact opposite of what your words (the 95% figure) convey.

So stop measuring "most helpful" in any other way than "when you have a 50% success rate, advantage is most helpful".

(Perhaps you meant "still helpful", Hemlock? As in "even when you enjoy a 95% success rate, advantage is still helpful.")

This has been a public service announcement. Thank you.

 

[FormerlyHemlock]

Stop stop stop.

Saying something like "if you fail your saves only on a 1 (95% success), advantage cuts your failure rate by 95%" does everybody a huge disservice, since you aren't normally interested in how much advantage specifically cuts your failure rate.

The pertinent number is: what is your probability sans advantage? what is your probability with advantage? Now subtract one from the other. This is the value of advantage you should be concerned about.

No, it really isn't, in the general case. This is exactly why I posted my PSA in #382. The method of analysis you've advocated is common but usually unhelpful in guiding tactically correct decision-making.

For example, with concentration saves, you're normally interested in exactly this metric: the failure rate. The lower your failure rate, the more risks you can afford to take without much danger of losing your concentration spell. E.g. a Moon Druid with Spike Growth or Conjure Animals needs to know his failure rate before deciding whether or not to shapeshift into a rhino and charge off into combat.

He doesn't care about subtracting his probabilities from one another. He wants to know how advantage will change his tactical options. If he's twenty times safer with advantage, he doesn't care if that's only (.9975 - .95 = .04975) by your metric. Your metric isn't what he's interested in.

 

[Njall]

No, it really isn't, in the general case. This is exactly why I posted my PSA in #382. The method of analysis you've advocated is common but usually unhelpful in guiding tactically correct decision-making.

For example, with concentration saves, you're normally interested in exactly this metric: the failure rate. The lower your failure rate, the more risks you can afford to take without much danger of losing your concentration spell. E.g. a Moon Druid with Spike Growth or Conjure Animals needs to know his failure rate before deciding whether or not to shapeshift into a rhino and charge off into combat.

He doesn't care about subtracting his probabilities from one another. He wants to know how advantage will change his tactical options. If he's twenty times safer with advantage, he doesn't care if that's only (.9975 - .95 = .04975) by your metric. Your metric isn't what he's interested in.

You're still off base, tho.
Saves work pretty much like AC, in that each successive point nets increasing returns to your survability, until the very last one which effectively doubles your effective health (assuming you're taking hit point damage).
With saves ( especially save or suck that rob you of your action for the round ) what matters is how often you pass rather than fail ( and thus you get your action, can attack without penalties and so forth ).

Assuming each PC deals the same DPR, for example, and you're dealing with a save or suck that prevents a PC who fails from acting, you'd better grant advantage to the guy which succeeds 50% of the time ( and, thus, now makes his save 75% of the time, thus granting the party an additional 2.5 rounds out of 10 of DPR, on average ) than to the guy which only has a 5% chance of not being screwed (and that would only gain like 1/2 rounds of DPR out of 10).

Yeah, the latter would act 200% as much, but the party would still benefit less from it than if you got the former to act 150% as much instead.

 

[FormerlyHemlock]

You're still off base, tho.
Saves work pretty much like AC, in that each successive point nets increasing returns to your survability, until the very last one which effectively doubles your effective health (assuming you're taking hit point damage).
With saves ( especially save or suck that rob you of your action for the round ) what matters is how often you pass rather than fail ( and thus you get your action, can attack without penalties and so forth ).

Assuming each PC deals the same DPR, for example, and you're dealing with a save or suck that prevents a PC who fails from acting, you'd better grant advantage to the guy which succeeds 50% of the time ( and, thus, now makes his save 75% of the time, thus granting the party an additional 2.5 rounds out of 10 of DPR, on average ) than to the guy which only has a 5% chance of not being screwed (and that would only gain like 1/2 rounds of DPR out of 10).

Yeah, the latter would act 200% as much, but the party would still benefit less from it than if you got the former to act 150% as much instead.

Yes, but it would be even better to give advantage to the guy who succeeds only on a 16 or better.

It depends very much on the details of the situation, but the point is that analyzing advantage in terms of "effective plus" is helpful only in one case that I know of: when you're trying to decide whether to cast Bless (+d4) or Circle of Power (advantage) since you can't concentrate on both.

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[Bacon Bits]

Ah, the absolute vs relative bonus mathematics argument. Is everyone ready to gouge their eyes out yet or does this need to carry on for another few pages?

 

[Njall]

Yes, but it would be even better to give advantage to the guy who succeeds only on a 16 or better.

It depends very much on the details of the situation, but the point is that analyzing advantage in terms of "effective plus" is helpful only in one case that I know of: when you're trying to decide whether to cast Bless (+d4) or Circle of Power (advantage) since you can't concentrate on both.

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How so? If you succeed on a 16+, that's a 25% chance of succeeding.
With advantage, that's 25%+ 18.75%= 43.75%, so you're only gaining 1.875 rounds of action out of 10 instead of 2.5.



[Edit: because basic math, or basic english, for that matter, seem to be out of my league at 5:30 a.m.]

 

[FormerlyHemlock]

How so? If you succeed on a 16+, that's a 25% chance of succeeding.
With advantage, that's 25%+ 18.75%= 43.75%, so you're only gaining 1.875 rounds of action out of 10 instead of 2.5.


[Edit: because basic math, or basic english, for that matter, seem to be out of my league at 5:30 a.m.]

I presume we're talking about the common 5E idiom in which one successful save removes the spell and puts you back in play. (That makes it bell-curved again.) For example, Confusion or Tasha's Uncontrollable Laughter. In this case, you're best-off helping the guy with the weakest save, within reason, in order to reduce the effective duration of the spell.

If you succeed only on a 16+, the spell will keep you out of play for (1/(1-3/4) = 4) rounds on average. With advantage, you'll be out of play for (1/(1-9/16) = 2.28) rounds on average. You've just gained 1.72 rounds of effectiveness.

If you succeed only on a 11+, the spell will keep you out of play for (1/(1-1/2) = 2) rounds on average. With advantage, you'll be out of play for (1/(1-1/4) = 1.33) rounds on average. You've just gained .67 rounds of effectiveness.

If you're the guy granting advantage, and you can only grant it to one person, you'll add more to party effectiveness by helping the guy who needs a 16+ than by helping the guy who needs 11+. Which brings us neatly back, full-circle, to non-proficient wizards with Foresight, who only get to grant advantage to one PC, which might be the non-proficient wizard.

This is what I meant upthread when I said:

Depends how you measure "most helpful". For example, if you fail your saves only on a 1 (95% success), advantage cuts your failure rate by 95%. If you fail 50% of the time, it cuts your failure rate by only 50%. This is good for e.g. concentration. On the other hand, if you succeed only on a twenty, advantage doubles your success rate, which can e.g. halve the duration of enemy spells on you.

It really isn't possible to generalize a specific point on the d20 where advantage is "most helpful." It depends on the details of the situation and what the save is being made for.

 

[Njall]

I presume we're talking about the common 5E idiom in which one successful save removes the spell and puts you back in play. (That makes it bell-curved again.) For example, Confusion or Tasha's Uncontrollable Laughter. In this case, you're best-off helping the guy with the weakest save, within reason, in order to reduce the effective duration of the spell.

If you succeed only on a 16+, the spell will keep you out of play for (1/(1-3/4) = 4) rounds on average. With advantage, you'll be out of play for (1/(1-9/16) = 2.28) rounds on average. You've just gained 1.72 rounds of effectiveness.

If you succeed only on a 11+, the spell will keep you out of play for (1/(1-1/2) = 2) rounds on average. With advantage, you'll be out of play for (1/(1-1/4) = 1.33) rounds on average. You've just gained .67 rounds of effectiveness.

If you're the guy granting advantage, and you can only grant it to one person, you'll add more to party effectiveness by helping the guy who needs a 16+ than by helping the guy who needs 11+. Which brings us neatly back, full-circle, to non-proficient wizards with Foresight, who only get to grant advantage to one PC, which might be the non-proficient wizard.

This is what I meant upthread when I said:



It really isn't possible to generalize a specific point on the d20 where advantage is "most helpful." It depends on the details of the situation and what the save is being made for.

Nope, I was addressing the (admittetdly less common) case where you're targeted by save-or suck effects each round and either save or sit out of action, each round.
On the other hand, while I see your point, it's worth mentioning that, given that most fight only last 3-4 rounds in 5e, cutting the duration of the spell from, say, 8 to 4 rounds might still not work to the party's advantage ( because combat might well be over before the spell expires anyway ).