When outside of initiative (battle), characters are able to shine through the use of ability checks. Non-initiative work is less stressful and chaotic than initiative work, so characters should shine if they have the talent for it.
To represent the more regular work a character can produce when not in battle, this variant rule lets characters roll 3d6 instead of 1d20 for ability checks outside of initiative. This rule, also known as the
bell curve roll rule, produces a range of odds that favors average results much more than extreme results.
Metagame Analysis
In general, this variant leads to a grittier game, because there will be far fewer very good or very bad rolls. Not only can you no longer roll 1, 2, 19 or 20, but most rolls will be clustered around the average of 10.5. With a d20, every result is equally likely; you have a 5% chance of rolling an 18 and a 5% chance of rolling a 10. With 3d6, there’s only one possible combination of dice that results in an 18 (three sixes, obviously), but there are twenty-four combinations that result in a 10. Players used to the thrill of rolling high and the agony of a natural 1 will get that feeling less often—but it may be more meaningful when it does happen. Good die rolls are a fundamental reward of the game, and it changes the character of the game when the rewards are somewhat stronger but less frequent.
Another subtle change to the game is that the bell curve variant awards bonuses relatively more and the die roll relatively less, simply because the die roll is almost always within a few points of 10. A character’s proficiencies, ability scores, and gear have a much bigger impact on success and failure than they do in the standard d20 rules.
Rules for Rolling
This system requires several changes to how rolls are made.
Advantage and Disadvantage
When you roll with advantage or disadvantage with a d20, you roll an additional d20 and pick the higher of the two. By default, advantage sources do not stack, nor do disadvantage sources. If you have one or more advantage sources and one or more disadvantage sources, you roll a straight d20, independent of how many sources there are.
For the bell curve roll rule, you can stack sources of advantage and disadvantage. You can have a number of sources of advantage up to or equal to your proficiency modifier and a number of sources of disadvantage up to or equal to your proficiency modifier. Add your sources of advantage (+1) and disadvantage (-1). Based on your result, you roll the dice pool in
Table 1. You cannot have a magnitude of a positive or negative value on this table greater than your proficiency modifier.
The reasoning behind this stacking is that it allows you to add more sources to help or hinder your attempts based on your expertise. A skilled character who is powerful (i.e. higher proficiency modifier) can, in the right circumstances, reach higher levels of greatness than a beginner (i.e. lower proficiency modifier). It also allows aiding a character to be more of a group effort. If more characters work together to aid a single roll, it can improve the probability of a great result even more.
For example, Joe Brown is playing a human who has a +4 to his Intelligence (Investigation) skill. He investigates a room after a battle. The room has dim light (disadvantage; -1) and he is being aided by two party members (advantage; +2). Thus, he has a total sum of +1 and rolls 4d6 and takes the highest 3 values, then adds his bonus of +4 to it.
Table 1: Advantage and Disadvantage Dice Pools
| Advantage/Disadvantage Sum |
Dice Pool |
| -n |
lowest 3 of (3+n)d6 |
| -6 |
lowest 3 of 9d6 |
| -5 |
lowest 3 of 8d6 |
| -4 |
lowest 3 of 7d6 |
| -3 |
lowest 3 of 6d6 |
| -2 |
lowest 3 of 5d6 |
| -1 |
lowest 3 of 4d6 |
| 0 |
3d6 |
| 1 |
highest 3 of 4d6 |
| 2 |
highest 3 of 5d6 |
| 3 |
highest 3 of 6d6 |
| 4 |
highest 3 of 7d6 |
| 5 |
highest 3 of 8d6 |
| 6 |
highest 3 of 9d6 |
| n |
highest 3 of (3+n)d6 |
Other Boons
Halfling's Lucky Trait
When you roll a 3 on the 3d6 for an ability check, you can reroll the dice pool and must use the new roll.
Wizard's School of Divination Portent Feature
A wizard can still use one of the d20's results on a bell curve rolled ability check. If the d20's value is a 19 or 20, it is treated as an 18. If the d20's value is a 1 or 2, it is treated as a 3.
Taking 10, 16, and 18
You can't take 20 using the bell curve variant. Instead, you have three options:
- Taking 10. This remains unchanged from existing rules. When your character is not being threatened or distracted, you may choose to take 10. Instead of rolling 3d6 for the ability check, calculate your result as if you had rolled a 10. For many routine tasks, taking 10 makes them automatically successful. Distractions or threats (such as combat) make it impossible for a character to take 10. In most cases, taking 10 is purely a safety measure —you know (or expect) that an average roll will succeed but fear that a poor roll might fail, so you elect to settle for the average roll (a 10). Taking 10 is especially useful in situations where a particularly high roll wouldn’t help.
- Taking 16. When you have plenty of time (generally 1 minute for a ability that can normally be checked in 1 round), you are faced with no threats or distractions, and the ability check being attempted carries no penalties for failure, you can take 16. In other words, eventually you will get a 16 on 3d6 if you roll enough times. Instead of rolling 3d6 for the ability check, just calculate your result as if you had rolled a 16. This makes the task take ten times as long.
- Taking 18. When you have plenty of time (generally a bit less than two hours for a ability that can normally be checked in 1 round), you are faced with no threats or distractions, and the ability check being attempted carries no penalties for failure, you can take 18. In other words, eventually you will get an 18 on 3d6 if you roll enough times. Instead of rolling 3d6 for the ability check, just calculate your result as if you had rolled a 18. This makes the task take one hundred times as long.
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