Gambling for Checks/Combat/Basically Everything

[u/Weird_Contribution38]

I've had this idea of a character with their mechanic where, along with their regular role of DC checks, attack rolls, etc., I was hoping for some ideas to help introduce this into a character I was thinking along the lines of a swashbuckler or magic wild sorcerer who can roll again to either a critical success or a critical fail. Obviously, the chances of losing should be higher to cancel out any overpowering effects. Any and all ideas are welcome! 5E

[u/Ok_Fig3343]

For attacks,

...the simplest thing to do is just increase critical hit and auto-miss ranges:

• Attacks score critical hits on a 19 or 20, rather than just 20 (doubling the odds)
• Attacks automatically miss on a 1 or 2, rather than just a 1 (doubling the odds)

The problem is that 5e has no "critical failure" rules: just automatic misses. Even when a natural 19 would have hit anyway, turning that into a critical hit is a huge boost in damage. But when a natural 2 would miss anyway, turning that into an automatic miss changes nothing. You gain more than you lose when you expand the ranges evenly!

You could try expanding the ranges unevenly, like this:

• Attacks score critical hits on a 19 or 20
• Attacks automatically miss when the roll is between 1 and 5

But again, those low rolls are the rolls that would usually miss anyway! The effect is negligible unless you're facing a particularly low AC enemy.

A more effective penalty might be giving a straightforward penalty to attack rolls:

• Attacks score critical hits on a 19 or 20
• You gain a -2 penalty to all attack rolls.

This means that, rather than turning low rolls into automatic misses, you're turning medium or even high rolls into ordinary misses. A 3rd level Rogue with +3 Dex and +2 Proficiency would normally a 20 AC monster on a roll of 15, but now it takes 17! You're going from a 25% chance to hit and a 5% chance to crit to a 15% chance to hit and a 10% chance to crit, basically losing 2 chances in 20 to deal normal damage in exchange for one chance in 20 to deal double damage.

For ability checks and saving throws,

... it gets more complicated.

5e has no concept of "critical successes" for ability checks or saving throws, and introducing one would be difficult, since there's no simple number (damage) that you can simply double.

Likewise, 5e has no concept of "automatical failures" for ability checks or saving throws, probably because having auto-fails but not critical successes would feel needlessly punishing.

The simplest thing to do would probably be introducing automatic (not critical) successes and applying a penalty, just like we did with attack rolls:

• Ability checks and saving throws automatically succeed on on a 19 or 20
• You gain a -2 penalty to all ability checks and saving throws.

But this introduces a few issues with ability checks in particular:

• Players might request (and succeed!) to do impossible or highly improbable things, seriously derailing the campaign if the DM doesn't shut them down.
• Players might request to do the same thing over and over until they succeed, rendering the skills and abilities of the party obsolete unless there is a penalty for wasted time or failed attempts.

To avoid this, I would limit the effect to ability checks that (a) have clearly defined effects and t, such as the Strength (Athletics) checks you make to grapple or shove, the Dexterity (Stealth) check you make to hide, the Wisdom (Medicine) check you make to stabilize a creature, or the spellcasting ability check you make to Counterspell.

None of these are checks that do impossible or highly improbable things, and none of these are checks that can be made over and over without wasting pressure rounds of combat.