The Anatomy of a Roll
In almost every system a dice roll - I'm using dice roll synonymously with skill check for the purposes of this - is made up of the same elements. First, you have a die or dice depending on the system. Second you have some element representing your character's natural abilities. Third you have some element representing your character's skill. Finally, you have an element representing specific outside factors like gear, or situational modifiers. You also have difficulty, but we'll touch on that later.
In D&D the die is a D20 and all the non-die factors boil down into small plusses or minuses. You get +4 from your high dexterity, + another 6 from your skill. +2 from your masterwork tools. These all combine so that you're rolling 1D20 and then adding 12 to the final tally.
In L5R you roll a number of dice equal to your ability + skill but only keep a number of dice equal to your ability. You also get bonuses or penalties based on situational modifiers like being wounded or it raining.
In the Storyteller system you also grab a number of dice equal to your ability + skill, then add more dice based on bonuses - or take dice away for penalties - and roll to count successes, crits, failures, and botches.
You get the idea. Different systems do it in different ways, but ultimately you have the same two core factors coming into the roll in some way: your character's natural ability and their skill.
So What Does the Die Represent?
Everything in the roll represents some facet from the game. We have dice or bonuses for our ability, the same for our skill, and the same for outside factors. What is the die for? Well, the die, or dice, represents chance. Now from a game mechanics stand point that seems obvious. The die is a random number generator, so of course it represents chance. But what I actually mean by chance is the die represents "variables outside of the control of the character that could influence things for the positive or negative."
The dice could be a bit of bad footing that robs you of a solid stroke - or the enemy of a solid defense. It could be a stray breeze that pushes your arrow off course, or guides it over the shield of the target. The dice could represent part of traffic shifting unexpectedly in front of you, or the car you are pursuing. It's whatever could go wrong, or right, at the moment in time when the characters needs it to do that. And that is worth keeping in mind.
Taking A 10
In D&D, ever since 3rd ed I believe, a player who is not under duress can choose to take a 10 on an action. 10 is a little below the average dice roll of 1d20 (the average being 10.5) and taking a 10 is how the game chooses a lot of things. Your passive perception, passive insight, and armor class - for example - are done by assuming you rolled a 10 on 1d20 then added the appropriate modifiers.
What taking a 10 represents is the level of ability your character can perform without putting in a ton of effort. A thief with +2 dex and +3 proficiency in lock picks can, without much effort when not under strain, pick a difficulty 15 lock. He could also pick a difficulty 20 lock, but that would take a "better than normal" effort from him or her.
Take this concept to the real life. I drive everyday. I drive in the morning. I drive in the afternoon. I drive at night. I've driven halfway across the country (or so it felt.) I've driven in the rain. I've driven in the snow. I've done all this and I haven't been in an accident in years. This is because, the vast majority of times, I'm able to take a 10 on drive checks (if we apply the mechanic) as I am not under duress, and my normal driving skill is superior to what is needed to drive safely under normal conditions.
Driving, in other words, is a routine thing. Like going up or down steps. Like riding a horse for a fantasy character.
This is where we get t he real last part of the roll: the difficulty. Difficulty represents - brace for it - how difficult the task trying to be accomplished is. Most games will give you a chart with example difficulties and a break down including Easy, Average, Challenging, and Difficult difficulties. Some go further. Others just stick to t he four I listed - or variations on that theme. Knowing the difficulty also tells you - if you care to figure it out - the odds of success.
For example, you have a 5% chance of getting any specific number on a D20. So if a player has a +6 total bonus to a skill (ability + skill) and you set a difficulty of 20, then the player needs to get a 14 on 1D20 to succeed. That means the player only has 7 faces on the D20 that are a success for them (14, 15, 16, 17, 18, 19, 20). In other words, a player who needs a 14 or better has a 35% chance of success on a roll.
Why is this important? Well, let's look at some of the easier tasks we talked about calling a roll for. How hard would you say it is to climb the stairs? Pretty easy right. Like, maybe a difficulty of 2? So if I have an Athletics of +4 and a strength of +3 why make me roll? Sure, I might get a natural 1, which depending on how you run might be an autofail, but 95% of the time it is just useless as anything I roll is going to blow the TN out of the water.
What about driving? Well, driving is also fairly easy. Accidents happen all the time, sure, but there are literally thousands of people on the road at any given time and the vast majority are not getting into an accident. Still, it's harder than climbing the stairs. So we put it at 10. But if I'm not under durress, and I am a driver who normally dirves quite safely, I'm also going to beat that most of the time, right? I mean, I'd have to be pretty unlucky to have it go wrong.
But let's change the situation.
I'm still driving, but now I'm running from the cops and I'm driving in the snow. Since I'm running from the cops I'm probably speeding. I'm being chased. There's loud noises (sirens). People ahead are moving erratically as they get out of the cops way, but maybe also try to help. Oh, and the ground is covered in snow. That sounds like a stressful situation doesn't it? And one that is going to have a much more fair chance of coming up bad for me. Why? Well, more things can go wrong, for one.
Everything Means Something
One thing I love about the Star Wars system by FFG is you can actually point out what every single thing in a roll represents. In most situations you grab a number of dice equal to your ability, upgrade a number of them equal to your skill, and then add boost dice for things in your favor. You do the same thing for difficulty, grabbing a number of dice for how hard the task is, upgrade those based on extra challenge in the situation, and add setback dice for other factors that could influence things against you.
What happens is that in the end you cancel out your successes and advantages with failures and threats, but you know exactly what is happening. The roll in and of itself tells a story. "Your skill carries you through most of it, but the guy chasing you is just as good. Luckily, you're faster on the stick than him and pull ahead, except the tightness of the terrain means you're not able to get out of range of his guns. Fortunately, your co-pilot is able to point out a way to keep as much cover between you and him as possible."
Now, the FFG system does this well, but it can be true in every game. Every part of a roll should mean something and contribute to the story. Did a player only not get hit because of their shield? Tell them. Did someone else get hit because they dropped cover? Bring it into the story. Importantly though, keep it in mind when you're asking for a roll.
Things To Ask Yourself
Ask yourself these three things when calling for a roll, and you'll find yourself having better drama everytime the dice hit the table.
- What gives this situation a chance to fail?
- Why is the difficulty set where it is?
- What random chance can the die/dice represent that would impact this endeavor?
Try for answers beyond "because it is" and weave it into your narrative. For example, in combat there is a chance to fail because weapons, noise, and chaos are going off all over the place causing distraction and tension in everyone. The difficulty is set where it is because that is the target's defined ability to defend themselves. As for what random chance the dice can represent, that can be anything per your situation, but there are some examples above.