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Difficulty Class Warfare
Legends and Lore
Mike Mearls

My name is Mike Mearls, RPG Group Manager for the D&D Research and Development team. Welcome to Legends & Lore, a weekly column where I write about various topics on D&D’s history, how the game has changed over the years, and where it’s going in the future. One of the things I want to do is pose questions and topics to D&D players across the world, because my real purpose is to understand what you think about D&D. Once I know that, then I can better understand the game.

Last week, I posted some musings on what skills might look like in D&D. I was all set to spend this week talking about the feedback I’ve seen on the forums and elsewhere. (Here’s a secret: It’s really easy to write a column when people ask questions and make observations on your work.)

But then Monte Cook (one of the major architects behind 3rd Edition and the d20 system) stepped in and made my life difficult. We were talking about skills and how they work, when Monte had what might be a really interesting idea concerning target numbers and Difficulty Classes. I happen to love it, but I’m biased. Other people I talked with in R&D were less enthusiastic about it, but I think that might involve my inability to explain it properly. So by writing it down and sharing it here, I’m hoping to get a better sense of its worth.

Up, Up, and Away

To start with, there are a few issues that have been a part of D&D’s approach to skills that I’d like to examine.

First, D&D skill checks have usually relied on a d20 or its five times as precise cousin, the d100. A moderately skilled character still faces the hazard of a poor roll leading to failure even at relatively low DCs or high chances of success. The routine skill check is almost always still dangerous in D&D.

Second, that pressure gives a big incentive for players to absolutely maximize their skills. With an increasing gap between the specialist and the guy who has made zero investment in a skill, a DM might have trouble creating appropriate challenges. The problem isn’t the skilled guy, but rather characters who have little chance of hitting a DC of even 10 or 15 due to armor check penalties or low ability bonuses.

Third, the specialist gains access to DCs that were meant to be rarely hit or the product of a phenomenal die roll. In 3rd Edition, a DC 20 Diplomacy check causes an enemy to stop attacking you. Even higher checks make them work with you. The idea is a good one, but there’s a strange line to walk for the designer in creating rarely hit DCs and the means by which a character can choose to increase a skill bonus. It’s an arms race that is supposed to end with those high DCs as challenging targets, but all too often creative players can find ways to stack bonuses to make such results trivial.

In the abstract, the idea behind setting a DC is twofold. It provides a way to realistically model difficulty. Some things are harder than others, and we expect characters to have a greater chance of failure when attempting them. This approach also allows a DM to see and make judgment calls using a relative scale. If pushing a laden cart is a DC 15 Strength check, then you can see that pushing a massive, stone statue might be DC 25 or 30.

The skill system then gives a way for a character to specialize in certain areas, turning what would be a daunting task for the typical character, that DC 25 check, and making it the equivalent of a routine action, DC 10 or 15. The skilled character does things that others characters simply can’t hope to do or would need some luck or natural talent (a high ability modifier) to achieve.

Leveling the Field

These issues all led Monte to make a proposal that I quite like. Bear with my description, as it takes a dramatically different approach to skill DCs.

In this world, a check DC is no longer a number. Instead, like several rules-light gaming engines, it uses a series of descriptors that illustrate the minimum skill level needed to attempt a task. This list gives the ranks from lowest to highest:

  • Novice
  • Journeyman
  • Expert
  • Master
  • Grandmaster
  • Impossible

When the DM asks for a check, you compare the DC to your rating in the appropriate skill. Impossible is essentially a placeholder, a rank that applies to things that the DM or the rules deems are doomed to failure. For example, a character who leaps off a cliff and flaps his arms in order to fly is attempting (and failing) an impossible task.

If your skill rank is greater than the task’s DC rank, you automatically succeed. You are so skilled that you can complete the task without any special effort. Think of a tightrope walker at the circus. She has enough training and experience that performing her act is an automatic success. It would take some outside factor, like a sudden injury, an equipment failure, and so on, to cause her to fall. On the other hand, as a sedentary game designer I wouldn’t even imagine trying to walk across a tightrope myself. I’d fall after a step or two.

If your skill rank equals the task’s DC rank, you need to make a check with a result of 15 or higher to succeed. You’re skilled enough that you might succeed. In this world, skill checks use an ability score modifier (chosen to fit the task by the DM; a skill uses whatever ability is the best match for the actual action) with perhaps a small modifier based on feats or a skill bonus.

Going back to our tightrope walker, perhaps an earthquake strikes in the middle of her act. As the rope sways, the DC shifts one category up. Now she has to make a check, perhaps with her 18 Dexterity for a +4 bonus as well as a +4 bonus from a feat or other benefit she took. That gives her a 65% chance to remain on the rope.

If your skill rank is below the task’s DC rank, you automatically fail. Your training and experience are not enough to complete the task. Going back to the tightrope walker, let’s say that as the earth shakes she also steps on a length of the rope that her rival covered in grease. The difficulty shifts one more category up, causing her to fall to the net below.

The DC is based on two things. First, the DM determines a task’s basic difficulty. Then, for each element in play that makes it more difficult, he shifts the difficulty down one rank to the harder level. For elements that make it easier, he shifts it up. Typically, the DM informs you of the DC before you make the attempt. A hidden threat might mean that you don’t know the true DC until you make your attempt, but that’s the exception rather than the rule.

Going back to our hapless tightrope walker, perhaps she is carrying a pole to help balance her. The pole gives her an advantage that shifts the DC down one category. When the earthquake hits, she still keeps her balance. When she steps on the greased section of rope, she must then make a check.

Benefits of this Approach

I will readily admit that is a radically different approach to skills in D&D, one that looks nothing like anything in any version of the game. I imagine that 90% of you are ready to lambaste it. However, it’s worth pointing out some of its benefits:

  • It dramatically simplifies the math and removes the escalating bonus race.

  • It speeds up play by eliminating die rolls in some cases.

  • It makes DCs the same across all levels. An expert task is always expert level. We don’t need to shift difficulties assuming that your bonus continually increases because some characters can remain untrained. The system works by removing the link between difficulty class and level. Instead, we just use a simple, descriptive system as applied to reality.

  • It allows trained experts to repeatedly achieve impressive results through practice and training. Just as in real life, a highly trained character can do amazing feats without any real risk of failure (barring any complications or unexpected hazards).

  • It more closely models the real world (in my opinion, at least) by shaping how we approach tasks. We have an innate sense of things we can do without thought, things that we know to not try, and things that can be challenging. I know that I can walk a mile in 20 minutes without any real effort. I can jog a mile in 15 minutes with some (OK, a lot of) exertion. My sedentary butt would collapse long before I hit a mile if I ran at a 10-minute pace. I don’t need to try these tasks to determine this. I have 36 years of experience to establish what I can do.

  • It makes skill training even more valuable because it grants automatic success in easier situations rather than a better chance of success. A sure thing is more valuable than improved odds (a bird in the hand versus two in the bush). A rogue highly trained in Acrobatics or Balance simply scurries across a tightrope while the fighter looks for another route. This approach actually encourages players to use their skills more often in dangerous situations by removing random, chance-driven failure as the norm.

  • It encourages smart play and engagement. A player with a clever idea can shift the DC one level and turn a check into an automatic success, or an impossible challenge into one with a chance of success. I personally like this because it gives the DM a lot of leeway to use the system to shape his or her game.

  • It bakes “impossible” directly into the game. No amount of Diplomacy can sway the raging, bloodthirsty barbarian. It’s off the chart. This may sound like a minor thing, but I think it’s important to set the expectation that the DM can simply invoke common sense or logic to rule that a check will fail regardless of the die roll. Relying on the rules to set what are meant to be impossible DCs is simply asking for trouble.

The Gaping Hole

This approach does not touch on opposed checks. I’ll talk about those next week, or perhaps talk about why you all either hated this idea or saw some merit in it.

Legends & Lore Poll Results: 08/09/2011

Last week's approach to skills is...

  • Good: 52.3%
  • Somewhere in the middle: 33.3%
  • Bad: 14.5%

Poll Time

Is this week's proposal a good or bad idea?
Neither – it has its strengths but it also has drawbacks.

Mike Mearls
Mike Mearls is the senior manager for the D&D research and design team. He has worked on the Ravenloft board game along with a number of supplements for the D&D RPG.

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