D20 open-ended

[Telperion]

I have usually gone with the traditional:
Natural 20 is a critical threat and an automatic strike or +10 in a skill check.

Last session, though, I used the open-ended style that is being used in various other systems.

It goes like this:
You roll a natural 20, and then you make another roll. If the new roll isn't another natural 20 you add your attack / skill total modifier + 20 + new roll into the check and sum them up. If you roll a natural 20 repeatedly then you keep adding a +20 to your check / attack roll until you roll something other than a natural 20.

If you roll a natural 1 you accrue a penalty of -20 and you roll again. Assuming the next roll isn't a natural 1 you do the same math as above, except in reverse, like this: Skill / Attack total modifier - 20 - new roll. If you roll more than one natural 1 in a row then you keep adding -20 to the check until you roll other than a natural 1.

In this way you can end up with truly spectacular or horrible results. Last session one player rolled a check result of 68 on a Survival (tracking) check, while another went of the deep end and ended up with -42. I also tend to accompany such extreme rolls with very memorable descriptions, since they really are Epic rolls. Whether for good or bad.

Now, my question is: does the open-ended system work for D&D?

I only allow open-ended rolls on a natural 20 or 1. This also means that a critical threat is no longer an automatic hit. You roll an 18 + you attack modifier, and the end result just might not beat a high level creature's AC. Should I extend the open-ended system, in combat, to also cover the threat range of any given weapon? So that a rapier would be open-ended on the following numbers: 1, 18, 19 and 20? What do you think? Is this broken or useable?

 

[Tonguez]

Stick with open ended for 1 and 20 only. Do criticals as they are now though

I use an open natural 20 too and it works great imho...

 

[Li Shenron]

I agree that you don't need extra changes.

However, I would never agree with you in using open ended rolls with skills. Attack rolls and saving throws (and possibly other less common rolls) are ok because the real difference is only if the final result is success or failure.
Instead, with skills (or other rolls which directly result in a degree or amount of success) you could possibly have a character roll a Jump check high enough to reach a mountain's top or a Listen check to hear atoms clashing... something they shouldn't do without magic or before they are far into epic levels.

 

[Yair]

You want a larger range of possibel results? I am actually considering using Fudge dice* instead of d20, to limit the affect of luck... to each his own...

If I would to implement open-ended rolls, I would keep them on a critical check in combat. Personally, though, at the very least I will allow them for Saves, Spell Penetration, Attack rolls, etc. - not for skills. The thought of a person with 0 ranks in Climb climbing mount Everest with a roll of 120+... shudders...

*For those not familiar with them - fudge dice are six-sided die marked with two '+1', two '0', and two '-1', so they average 0 and do not change the average roll regardless of the number of dice rolled. The number of dice rolled only affects the extremes of luck possilbe, in a fairly thin bell curve distribution (there is really no point of rolling too many fudge dice - you might as well fill out a lottery ticket).

[Edit: added explanation of fudge dice.]

 

[RuminDange]

I've been using the open-ended d20 roll IMC since the ELH came out.
So far it has caused no problems with skills going way out there. Most the skill rolls the party does that even comes close to going over a 100 is their best skills that are maxed with thier prime attribute modifying.
I keep the critical threats the same, and the original roll still has to hit to even threaten a critical.
ie. If you roll a 19 using a longsword and the total comes out to 35 to hit, and the person has a 36 AC, then no hit, no critical. But if you roll a 19 and get a total 40 to hit then you now threaten a critical and roll again to see if it is critical.
If your first roll is a 20 then you keep rolling and adding 20 to the result until you don't roll a 20.
If your first roll is a 1 then you keep rolling and subtracting 20 to the result until you don't roll a 1.

The only complaint so far is from one player (The better half) who has a d20 die that likes to roll 3's and 1's a lot of the time.
I have never liked the Natural 20 automatic hit or the natural 1 you're screwed results.

RD

 

[Coredump]

I don't think it breaks anything, but I really don't think it adds anything.

The way you were doing it is basically the same, you roll a 20 and then 'assume' the next roll is a 10. It takes away the randomness of the second roll, and removes any chance of continuing.

I think that is a good thing, because it simplifies it, and doesn't take away much.

Rolling 2 20's in a row is only a .25% chance (1:400), just isn't going to happen very often. Now lets say that is about 2-4 weeks worth of gaming. How many of those times will it actually *matter*? How often are you in a situation where rolling a 48 is much different than rolling a 30?? If you need to *roll* a 40+ to hit some monster, you should probably be running instead.

So, IMO, it adds a mechanic, and gives very little benefit.

.

 

[The Spectrum Rider]

IMC, for quite a few years, we've used the following "smooth" open-ended system: roll two d20's, a "value die" and a "continuation die." If the continuation die is 19 or 20, roll again and add the new value to the former value; if it's 1 or 2, roll again and subtract. When you roll again, you also roll the continuation die again, so it's possible (although unlikely) to keep going up, keep going down, or even go up and down for a while.

I know, I know: "too much dice rolling!" But in fact, my players and I love it. We're very accustomed to it, so it doesn't take much effort. And when the continuations come up, it focuses people's excitement a little.

I've seen people roll a 73. And a -54. I, and the other people who DM, have no trouble capping overly high Jump rolls and the like. But, in fact, it hardly ever comes up.

One word of warning: this makes rolls of 20 or more about 5% more likely. So we don't have any "1's always a failure, 20 always succeeds" rules (who needs 'em?!), and we increase all crit threat ranges by 1. That is, if a weapon ordinarily threatens a crit on a 20, in our game it needs a 21 or higher. (If you have multiple factors contributing to the crit threat range, work them out by standard rules *first*, then add 1.)

We've also included Bonus Points (extra effect for very high rolls) and Penalty Points (fumbles for very low rolls), and we have a system of Hero Points (rarely-replenished resource for making a "heroic effort"). What's surprising is just how *little* we've had to change the rules in order to incorporate these. The feeling of "anything can happen!" (even if it usually doesn't) makes the games quite exciting.

The Spectrum Rider