Echelon, being derived primarily from the *Revised System Reference Document*, uses a d20-based task resolution system.

Pretty much all character-initiated actions that can pass or fail have the decision made with a single die roll:

d20 + modifiers >= Difficulty Class (DC)

This is about as simple as it gets, really. A consistent mechanic, easily remembered, and I aim to keep the number of modifiers somewhat lower than typically seen in D&D 3.x or Pathfinder. I have noticed that players often try to acquire multiple small bonuses because the aggregate cost (in whatever resource is being measured, be it gold, experience points, or spell slots) is generally lower than paying for one big bonus.

I can’t be bothered, so a small number of larger bonuses, for much the same net effect, will satisfy the purely numeric part.

## Degrees of Success and Failure

Dungeon & Dragons 3.x and Pathfinder appear to run quite handily on a pass/fail mechanic, almost entirely. There are a few places that consider degrees of success and failure, but they are pretty uncommon. Critical hits and Climb checks are about the only ones that come immediately to mind. A percentage of successful hits can do extra damage, and a Climb check that fails by five or more points means the climber falls.

While most checks are pass/fail, some allow you to try for better results by changing the check DC, or taking a penalty to the check, which is much the same difference most of the time. This is not the same as degrees of success because you will either pass or fail, just with lower chance of success but better results.

It seems degrees of success or failure depend on how much higher or lower you rolled than the DC. If the DC is 15 and your check totals 20, you have succeeded by 5. If the DC is 15 and your check totals 10, you have failed by 5 (and if climbing… well, you aren’t any more).

This is not a bad rule and can be extended, with success by five, ten, fifteen, and technically more, if your check modifier is more than the DC itself.

This mechanism requires totally the d20 roll and modifiers, then subtracting the check DC to find the specific degree of success or failure. This isn’t *usually* difficult, but it can be after a few hours of gaming (and frankly, drinking, in at least some of the groups I play with). However, there is a quicker and easier way.

### Degrees of Success by Examination

I have noticed that often in play success or failure is evident almost immediately on rolling. If my fighter is trying to hit an opponent and I roll an 18, I have almost certainly hit. If I have to check carefully it means that we probably shouldn’t be trying to hit it with weapons, and should either fall back on magic, bug out, or suddenly get very clever. Similarly, a 4 almost never hits, regardless of modifiers, because that means we have horribly outmatched our opponents.

Now, in both cases I could work out the total check result and compare to the DC (Armor Class in the case of an attack), then subtract one from the other (the check minus the DC for the successful one, or the DC minus the check for the failure, unless I’m willing to deal with negative numbers). Annoying.

Consider for a moment, if I need a natural 20 to hit my target, I can only ever barely succeed (succeed by 0). If I can succeed on a natural 18-20, I can succeed by 0-2. Similarly, if I fail, I will fail by 1-19 or 1-17 (depending whether my DC was 20 or 18, respectively).

Say, that looks very suggestive.

Instead of working out exactly how much I succeeded by, why not just look at the natural roll and work with that?

A natural 1 will almost always fail, so it should be a minor failure. If I fail on a natural 19, though, I am either desperate or foolish to try it, because a natural 19 being a failure almost never happens. In fact, it happens exactly as often as rolling a natural 1 when I need a natural 20 to succeed. In exactly the same way, a success on a natural 2 will almost never happen; it means I could have succeeded on a natural 1 or lower.

Consider the following table.

d20 |
Success |
Failure |

1-5 | Superior | Normal |

6-10 | Greater | Increased |

11-15 | Increased | Greater |

16-20 | Normal | Superior |

This allows for up to eight levels of success and failure, and it probably looks exactly backward, I am sure. When you succeed, you want to succeed with the lowest possible roll on the die. 18-20 gives you pretty certain success, but the effect is likely to be small. However, it is mathematically the same as rolling 0-2 points higher than you needed to beat your check DC. In the same way, if you’re going to fail you probably want to fail with the lowest roll possible in order to minimize the effect of failure. Rolling a natural one and failing is in this model the equivalent of rolling one point less than you needed.

A modifier still has the same overall effect, since we look only at the natural die roll. A +1 improves my chance of success, so I might succeed on a natural 13 where previously I would have failed… but now it’s the difference between a natural failure and a natural success. If I could previously have succeeded only on a natural 8 or higher, that +1 means I could succeed on a natural 7 now and possibly get a better result… just as under the common subtractive model that +1 might move me from a total check result of 23 to 24 and thus move me from “DC+5″ result to “DC+10″ result.

I am inclined to drop rules such as “20 always hits” and “1 always fails”. If you need more than a natural 20 to do something you probably shouldn’t be doing it in the first place, and if you can only fail on a natural 1 because the rule says so you should be allowed to succeed without the check.

## Closing Comments

Basic task resolution is just that: basic. It is entirely serviceable, but many people like to see a little more differentiation in degrees of success.

To do that, the obvious mechanism is to compare the total check result against the Difficulty Class of the check. Easily explained, but I find it annoying in practice because common cases, obvious success and obvious failure, still require a lot of work to be done. Depending on the mental state (fatigue and inebriation) this could be more trouble than people are willing to do, and error prone.

Instead, going to an examination method allows the obvious success and failure cases to be handled very quickly using a standardized table. The only time it is necessary to work out the exactly check result is when it is a borderline case… in which case the additional effort determines whether it is a greater success or greater failure.

This does take away from the “20 is always best!” idea, and I admit I’m not really excited about that because I like rolling natural 20s as much as the next guy. I think in the end that if I want to include degrees of success in a convenient and functional way, I can live without “20 is always best!” pretty easily.

So would a “great” success/failure replace the idea of a critical success/failure? I guess it would be impractical to use natural-1 and natural-20 for the latter at the same time as your above approach.

I just threw out arbitrary ranges and descriptions. I don’t think criticals, as used by D&D 3.x, can really apply here.

Critical hits in D&D 3.x are typically first natural 20, followed by a confirmation roll (second attack check against the same AC). It means basically that 5% of all successful hits are criticals. That applies to all combatants, even those that have very little chance of hitting at all.

Moving to a model like this means the improved effects only happen if you are more skilled and removes the straight luck from it. I’m okay with something like “improved success gives an extra die of damage” or something. You don’t have to confirm, but you have to be good enough to hit your target on a low roll.

Actually, this suggests the grades above are too strict. normal success on 8-13 means that a “reasonably challenge” with 50% success will only get normal success… about 15% of the time. That can’t be right.

This clearly needs some tuning — the principle is sound, the application is a little whacked.

I just changed the table. The new one is simpler and I think it’ll work better. Success is success and you just get better from there. It might be worth softening failure a bit, with 1-5 being “barely failed”. This covers cases where you don’t achieve your actual goal but might be able to recover. Climb checks, you just can’t make progress this round (but don’t fall), Jump checks may mean you didn’t quite reach your goal but are close enough to catch the edge with your hands and pull yourself up, Craft checks mean you didn’t ake progress but didn’t ruin it, and so on. This is mostly a matter of the label, but a better label may make it easier to remember to treat this way.

Success could be the same. “Barely successful” still is successful, with normal effect, but it’s not particularly special.

I must be brain-dead today because I don’t understand your “simpler” system at all. Don’t take this as a big deal, but it might mean you need to rethink how you explain it.

I can see one minor objection, or maybe not an objection but an observation: you are assuming that the PCs are almost always facing on-level or near-level competition. Can’t my heroic fighter have fun carving his way through an army of wimps? “I succeed by 27 and kill three adjacent goblins in one blow”

One more example of success degree: Knowledge rolls, with each +5 giving “one more piece of useful knowledge.”

I was somewhat distracted by the election last night. I’ll look the post over later and see if I can explain better.

However, I’ll see if I can explain now.

Assuming the game doesn’t fall off the RNG (Random Number Generator), when checks are needed it should be necessary to roll somewhere between 1 and 20 on the d20. As long as you can’t “always fail” or “always succeed”, this’ll work.

I am basically inverting the interpretation of the roll. This is more easily seen for the failure case, but the same principle works for success.

In the normal “degrees of failure” model, if I need at least a 12 on the die (12+mods = DC) then rolling an 11 is “failed by one”. Rolling a 1 is “failed by 11″. If I know I need a natural 12 or better then this isn’t so bad, but there are a couple of complications. First, everyone is likely to have a different target natural roll. Second, we probably don’t know what that is yet, until we have a bit of practice against this task. Until I have figured out my target natural roll I have to (roll d20, add modifiers, subtract DC) each time until I figure it out… and as soon as something changes the modifiers or DC, I get to start over. Everyone trying to do the task gets to do the same thing — especially when the natural roll is toward the outside of the range, 1 and 20 are where you can expect to find the biggest degrees of failure and success, even when you often know easily they are a failure or success.

Now, considering the failure, where I rolled too low. I can only ever fail from 1..11 points. I can subtract my total roll from the DC to find the degree of failure, subtract my natural roll from 12 (since I know that’s what I need, eventually) to find out how much I failed by, or simply look at the natural roll, since that is in the range of 1..11.

If the natural roll required was 10 instead (DC two points lower or modifier two points higher), I can only fail by 1..9 points. I cannot fail by 10. The natural roll will again fall in the same range, so why not use it?

The same principle, but with different numbers, applies for success. If I need a natural 20 to hit, I can only ever succeed by 0. If I can hit on natural 14 or higher I can succeed by 0..6. I can do all the math (d20+mods-DC; nat roll – nat needed) or examine (16-20 is a standard success, 14-15 is a better success). Whether you do all the math each time or not, in this case you have a 25% chance of standard success, 10% chance of increased success, 15% chance of great failure (“failed by more than 10″), 25% of increased failure, 25% of normal failure.

Why do more work than you need to?

It seems to me that you’re wanting to compare roll > DC-skill-mods instead of roll+skill+mods > DC. If so, I have no objection. I suspect most people want to know “what do I roll to hit?” anyway.

It’s a bit more immediate that way, if you know what die roll you need ahead of time. In the case of asynchronous play, such as on a forum, it’s extremely valuable because you can describe your success/failure without having to wait for a round-trip through the GM.

… I had not thought to express it that way, but you have a very good point.

However, the modifiers can change from character to character, the DC doesn’t. I would think it easier to keep track of as “d20+mods >= DC”.

Which is disappointing, because “d20 >= DC – mods” is easier to explain, it just doesn’t look like it would work in the face of different modifier totals.

What about just giving the DC and having each player modify it himself? It often ends up being done just like that anyway, right? Saves the GM trying to remember everybody’s list of possible modifiers.