In Defence of 4d6-4

I am a big proponent of using a modified core dice roll in D&D 5e.

In most of my games, I prefer to use 4d6-4 instead of d20 for skill checks, which reduces the randomness and creates a nice probability bell curve.

© Jasper Flick, anydice.com

Why?

1. It makes proficiencies really matter.
2. It reduces the opportunity for slapstick comedy (e.g., the paladin in full plate mail is highly unlikely to out-stealth the rogue).
3. It doesn't eradicate extreme results; there's still enough randomness to be exciting.

How does it work?

Instead of rolling a d20 for an ability or skill check, you roll a 4d6 - 4 and then add your bonus.

For example, if before your stealth modifier was +5, you'd now roll (4d6 - 4) +5.

Keeping in mind typical DCs as described in 5e RAW, it's easy to see why this starts to make sense:

• 5 - Very Easy
• 10 - Easy
• 15 - Moderate
• 20 - Hard
• 25 - Very Hard
• 30 - Nearly impossible

Take, for example, a Rogue at Level 1, with a +5 stealth. Using a d20 roll, they have a 20% chance of failing a DC10 stealth check. A paladin with no proficiency has a 45% chance of failing the same check.

If you consider that DC10 is meant to be "easy", a stealthy rogue should pass it almost every time, but the clunky paladin should not.

A core 4d6 - 4 roll solves this by creating a bell curve which means most rolls are closer to an average result.

Rolling lower than a 5 is very rare, and our rogues +5 makes hitting that DC10 truly easy (as the rogue only has a 5.4% chance of failing it). What about the paladin? The paladin still ends up having a 45% chance of failing, because he has no bonus to the roll.

Combat

Combat is a different story.

The modified roll has no chance of a critical result, which is core to 5e combat mechanics. It also narratively makes sense that characters are less likely to perform consistently in combat, achieving heroic feats and also suffering dismal failures.

So for attack rolls and saving throws, I stick to a d20.

Hold on, isn't all that rolling and math a pain in the ass?

Yes, if you were to do it with actual dice at a table, it would be.

But if you're running the game through a VTT, the actual dice are meaningless and it's easy to automate these rolls into a macro.

Every group I've tried this with have ended up loving it. Sure, they were skeptical first, but they all came to see the benefit.

Give it a try, you may just like it.