Critical Skill Checks an Alternative Rule for D20 (DnD/Pathfinder/Starfinder/+)

Critical Skill Checks an Alternative Rule for D20 (DnD/Pathfinder/Starfinder/+)

Lawrence Cutlip-Mason

In our gaming group of 25+ years, we ran an epic D&D 3.0 campaign that brought us face-to-face with a long-standing issue in D20 systems: the lack of critical successes and failures on skill checks. Unlike attack rolls and saving throws, skill checks don't reward rolling a natural 20 or penalize rolling a 1, which feels inconsistent and unintuitive. This leads to two big problems: high-skill characters almost never fail, and low-skill characters have no chance to succeed, even with a natural 20. While it might seem tempting to introduce a blanket rule of "natural 20 always succeeds, natural 1 always fails," this can lead to some really awkward, overpowered, or overly harsh outcomes.

We found our solution in the Dungeons and Dragons 3.0 Epic Level Handbook, page 110, under the heading "Variant: Open-Ended Rolls." We chose to apply this rule exclusively to skill checks and found no need to extend it to other mechanics, even in 20+ level campaigns. Over two decades later, we still use this rule in every D20 system we play.

Introducing critical successes and failures to skill checks brings a new dynamic to the game: even the most unlikely tasks can succeed, the simplest ones can fail, and occasionally, the results are downright hilarious. After years of playtesting, we've found this rule strikes a perfect balance—it doesn't unfairly punish characters with high skills, nor does it overly empower those with low skills. It just works.

The Rule in a nutshell

Whenever you roll a natural 1 or 20 on a skill check, follow these steps:

Critical Failure (Natural 1):

    • Roll again and subtract 20 from the result.
    • If you roll another natural 1, subtract another 20 and roll again, continuing this process until you roll something other than a 1.
    • Add your skill modifier to the final result.

Critical Success (Natural 20):

    • Roll again and add 20 to the result.
    • If you roll another natural 20, add another 20 and roll again, continuing this process until you roll something other than a 20.
    • Add your skill modifier to the final result.

Examples:

    • A character with +11 Stealth rolls a 20, then another 20, and then a 5. The result is 76 (20 + 20 + 20 + 5 + 11). They are so stealthy they might as well vanish from existence!
    • A character with a +5 Perception rolls a 1, then an 11. The result is -4 (-20 + 11 + 5). The character notices very little—possibly not even their own surroundings!

Clarifications

You do not keep rolling when you roll opposite of the original number, just add your skill to the numbers rolled. This prevents from going from a good roll to a bad roll and limits a weird chain affect.
  • Example 1: You have a Knowledge Check of a 7, You roll a 20 on the check and then you roll a 1, for a total of 28 (+20+1+7)
  • Example 2: You have a Jump of a 3, You roll a 1 on the check and then you roll a 20 for a total of a 3 (-20+20+3)

DM Tips

Really sky is the limit, the best bet when something completely weird happens is just make up a good plot point and run with it.

Example:

Someone rolled four 20's in a row and got a 92 Search check, the DM made up on the fly that the person found a dead scout with a map of the area with Points of Interest, including adding a "storage cache". This helped move the story along a little faster and gave some extra help to otherwise lost PC's.

This rule should apply to PC's and NPC's/Monsters equally, It favors the PC's more in the end but it's not remotely overpowering, you can roll equally good or bad (same chance).

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