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View Full Version : Automatic Fail/Succeed on 1 or 20 vs -10/+30 modifiers



Aeromyre
2010-06-11, 09:56 PM
Aside from D&D i play Mutants and Masterminds, where my brother, bestfriend and I swap GMing. But anyway in a book it maybe core, or maybe the Mastermind's manual that suggests instead of automatic failure or success for rolling a 1 or 20 respectively on a D20 you add a modifier or -10 or +30 when these numbers are rolled.

So if a characters with 14 strength attempts to lift a bolder off of his fellow adventurer he will fail on a natural 19 with a modified roll of 21 assuming the DC is around 40ish but if he rolls a natural 20 his modified roll is 52, so he somehow manages to do it.
Or it can simply be a measure of success, player needs to make a DC 10 check to notice a ship at sea, rolls a natural 20 gets 50+ modified and so he can see every detail on the ship.
On the other hand rolling natural 1's are for simple tasks that the player could normally succeed on a 2 so say a character has +13 to craft and the DC is 5 he rolls a 1 and his modified roll is a 4. but if his modifier is +14 he would succeed.

Thoughts on this system? Do you like it? Do you already use it? Will you use it now?

Do you think it's too rare to see DCs higher than 50? and on the opposite hand players simplly take 10 on skill checks as low as 5?

KillianHawkeye
2010-06-11, 10:00 PM
Are you sure you're understanding this correctly? I don't play Mutants & Masterminds, but it seems like such a system would make more sense replacing the 1 with a -10 and the 20 with a 30, not adding +30 to the 20 you've already rolled. At least, I've seen D&D house ruled that way before (with the replacing, not the adding).

Aeromyre
2010-06-11, 10:03 PM
No you add the modifier, I'm absolutely sure of that

KillianHawkeye
2010-06-11, 10:04 PM
Well, that's... extreme.

Harperfan7
2010-06-11, 10:09 PM
In core D&D, there is a variant rule that a 1 adds -10 and a 20 adds +10.

And lifting a boulder isn't a check, you are either strong enough to move the weight or not.

KillianHawkeye
2010-06-11, 10:10 PM
In core D&D, there is a variant rule that a 1 adds -10 and a 20 adds +10.

Yeah, that's what I was thinking of. But I guess M&M is way crazier than D&D (probably on account of being much further along in the alphabet).

Aeromyre
2010-06-11, 10:16 PM
Well, that's... extreme.

Yeah it sometimes calls for the incredibly impossible things to happen and therefore incredibly high DCs on occasion



lifting a boulder isn't a check, you are either strong enough to move the weight or not.

It was a purely hypothetical situation that (if it did require a check) would require it to be that high

The Dark Fiddler
2010-06-11, 10:23 PM
No you add the modifier, I'm absolutely sure of that

I'll admit that I'm not looking at the book right now, and I'm tired, and it's been a while, but I'm certain that the proposed rule was that natural 1 equals -10 and natural 20 equals 30.

Anyway, I switch between that and auto success/failure. Both seem to work, but auto seems to be the favorite of my players.

Aeromyre
2010-06-11, 10:34 PM
"Rather than automatic success or failure, you can choose to treat a
roll of a natural 1 as a –10 modifier for a check or roll and a natural
20 as a +30 modifier. This means characters are more likely to fail
on a natural 1 and succeed on a natural 20, but are not guaranteed
to do so, depending on their relevant traits. So, an especially
capable character could generate a modifier of –10 and still succeed
on a check, while a character with a poor or average trait could generate
a modifier of +30 and still fail a check with a high enough
Difficulty."

I suppose it could be interpreted either way.
They do say added as a -10 modifier, but thats somewhat confusing, if it was treated simply as -10 why bother saying modifier?

erikun
2010-06-11, 10:39 PM
Yeah, I've seen that variant is several different systems. Every time, it's been natural 1 = -10 roll and natural 20 = +30 roll. So if you had a +19 modifier and rolled a 20, the total would be a 49.

In either case, it doesn't matter much. Rolling +30 or even +50 is virtually always a success against any reasonable number anyways, which means there isn't much difference between that and the normal auto-succeed in most games. The only time I've seen it come up is in high-level D&D, where even rolling -10 isn't a failure for skilled characters and rolling +30 isn't a success for untrained skills. In other words, you end up with characters who literally cannot fail at some tasks and literally cannot succeed at others, which kind of tosses the whole "random chance of success or failure" it is supposed to represent out the window.

I don't use that variant.

Crafty Cultist
2010-06-11, 10:44 PM
I've seen a variant where on a natural 20 you reroll and add 20 from the reroll. if the reroll is another natural 20 you would reroll again and add 40. for a natural 1 you sbtract 20 instead

Aeromyre
2010-06-11, 10:45 PM
Yeah, I've seen that variant is several different systems. Every time, it's been natural 1 = -10 roll and natural 20 = +30 roll. So if you had a +19 modifier and rolled a 20, the total would be a 49.

In either case, it doesn't matter much. Rolling +30 or even +50 is virtually always a success against any reasonable number anyways, which means there isn't much difference between that and the normal auto-succeed in most games. The only time I've seen it come up is in high-level D&D, where even rolling -10 isn't a failure for skilled characters and rolling +30 isn't a success for untrained skills. In other words, you end up with characters who literally cannot fail at some tasks and literally cannot succeed at others, which kind of tosses the whole "random chance of success or failure" it is supposed to represent out the window.

I don't use that variant.

yeah but then at the same time 1 number has a 5% chance of being rolled on a d20, and so if something is supposed to be incredible unlikely then why would it have a 5% chance of happening?

but most of the time it functions the same as auto success

Gralamin
2010-06-11, 10:50 PM
I've seen a variant where on a natural 20 you reroll and add 20 from the reroll. if the reroll is another natural 20 you would reroll again and add 40. for a natural 1 you sbtract 20 instead

Thats called an Exploding d20.

Average roll of an exploding d20: 11.0526316
Average roll of -10 / +30: 10.45 - This rule actually slightly decreases the average roll of the die, making it less advantageous.

erikun
2010-06-11, 10:50 PM
If you dislike the 5%, you can always ask for a confirmation.

Roll a 1 > roll d20 again > only autofail on a second 1
Roll a 20 > roll d20 again > only autosucceed on a second 20 (this will likely be a confirming critical roll anyways)

You've reduced the chance of an automatic success/failure down to 0.25% each. Personally, I don't mind the current 5% chance, especially given that virtually every natural 1 or natural 20 would fail or succeed in a given senario anyways.

Daremonai
2010-06-12, 02:51 AM
My DM uses the 1=-10, 20=+30 variant, and it works well for us so far, both in low and high level games. For the most part it does mean that a one is a failure and a 20 is a success, but for those situations where it doesn't (a high modifier vs. a piddling DC or a low mod vs. astronomical DC) it makes far more sense than having a 5% chance of failure or success regardless of outside conditions.

Having a near-godlike wizard or Cleric with an unbreakable will of iron fall over and go to sleep just because a neophyte priest told him to (1st level cleric with Command) just breaks suspension of disbelief for me, even if there's only a 1-in-20 chance of it happening.

DonEsteban
2010-06-12, 05:02 AM
Modifiers to skills are hardly ever truly gamebreaking. I find that a span of 20 points is already pretty wide for skill checks (and much more for ability checks), which is why I sometimes even replace the d20 with 3d6.

What intrigues me: What happens to the take 20 rule? Do you just take 50 now? :eek:

GoodbyeSoberDay
2010-06-12, 05:17 AM
Thats called an Exploding d20.

Average roll of an exploding d20: 11.0526316
Average roll of -10 / +30: 10.45 - This rule actually slightly decreases the average roll of the die, making it less advantageous.You're calculating the average assuming the sane interpretation of the -10 +30 houserule. If you calculate it where a natural one ends up being a -9 and a natural 20 ends up being a 50, the average is 11.5; it doesn't matter, though. Like people have already said, in most cases the success rate of the d20 doesn't change.

Emmerask
2010-06-12, 06:08 AM
Aside from D&D i play Mutants and Masterminds, where my brother, bestfriend and I swap GMing. But anyway in a book it maybe core, or maybe the Mastermind's manual that suggests instead of automatic failure or success for rolling a 1 or 20 respectively on a D20 you add a modifier or -10 or +30 when these numbers are rolled.

So if a characters with 14 strength attempts to lift a bolder off of his fellow adventurer he will fail on a natural 19 with a modified roll of 21 assuming the DC is around 40ish but if he rolls a natural 20 his modified roll is 52, so he somehow manages to do it.
Or it can simply be a measure of success, player needs to make a DC 10 check to notice a ship at sea, rolls a natural 20 gets 50+ modified and so he can see every detail on the ship.
On the other hand rolling natural 1's are for simple tasks that the player could normally succeed on a 2 so say a character has +13 to craft and the DC is 5 he rolls a 1 and his modified roll is a 4. but if his modifier is +14 he would succeed.

Thoughts on this system? Do you like it? Do you already use it? Will you use it now?

Do you think it's too rare to see DCs higher than 50? and on the opposite hand players simplly take 10 on skill checks as low as 5?


I very much dislike the auto success auto fail method because:
I have a 5% chance to jump to the moon... REALLY?

The static bonus of +x -x is okay I think though I like my system if you roll a 20 or 1 roll again and add/subtract a lot more :smallwink:




What intrigues me: What happens to the take 20 rule? Do you just take 50 now? :eek:

Take 20 just remains take 20 no "skill-crit" or bonus whatsoever :smallwink:

DonEsteban
2010-06-12, 06:25 AM
I very much dislike the auto success auto fail method because: I have a 5% chance to jump to the moon... REALLY?
Well, you normally don't because there is no automatic success on skill checks for just this reason. But you have a 5% chance of hitting the moon with an arrow*.



Take 20 just remains take 20 no "skill-crit" or bonus whatsoever :smallwink:
Yeah, but what prevents me from just rolling 20 times until I get a 20?


*Well, no you don't, because of maximum range...