“Anytime you are out numbered the odds are stacked against you.” Sage advice from Matthew Colville to his players.

I was watching one of the Geek and Sundry RPG lite advice videos on YouTube where Santine Phoenix interviews Mr Colville about planning encounters. When he dropped this nugget of advice that he gives his players at the start of a session.

In the video he does briefly explain why this is the case, using terms such as action economy, and the chances to hit as the reasons why.

So what now follows is an attempt to explain as best I can Matts reasoning behind that statement based on his comments in that video and also another video of his about dice and probabilities.

I apologise now if the following seems confused and incoherent.

D&D uses a 20 sided die or d20 to determine if you are successful when attempting to do anything, like for instance hit an enemy.

The probability of rolling any single number, for example a 5, is 1 in 20, assuming that the die is a fair die.

So to roll any number on a d20 we have a 5% chance of rolling it.

In D&D we are not rolling for a single number but a number that is equal to or greater than a target number, like an armour class of an enemy.

So the probability of rolling a 13 or higher is worked out by adding the probabilities of rolling all of the numbers together.

Let’s look at a creature that has an AC of 13. Well I’ve just shown that we have a 40% chance of getting 13 or higher when we roll a die. Which means we would fail to hit our enemy most of the time. That’s not fun.

But what I haven’t accounted for are any modifiers that can be applied. Let’s assume I’m attacking with a sword that gives me a +3 modifier. So instead of having to roll 13 or higher to hit, all of a sudden I need to roll 10 or higher.

Which using similar math to above means that to hit an AC of 13 I’d have a 55% probability of hitting. I am now more likely to hit than miss. Now that’s more fun. And the bigger that modifier is the more likely I am to hit.

Now we jump to the action economy part. And we are specifically looking at combat here.

On a turn a player and enemy can do basically 3 things, with players getting a bonus action as well under certain conditions, that monsters rarely get. Plus a reaction. So players can have between 3-5 actions, while monsters get 3-4.

But in reality that translates to 1-3 actions that players can use to do damage, and 1-2 actions for monsters.

So as you can see on a 1v1 match up, the player has more chances of success at doing damage. And therefore the “advantage” and more likely to kill the monster before the monster kills them.

Any encounter that has equal numbers or less monsters than the party size means that the party has the advantage. They have more actions, and the greater chances to succeed doing damage.

But as soon as the monsters start to out number the party. The number of actions and those opportunities to hit start to sway in favour of the monsters.

So that’s why a group of goblins may not seem dangerous to a party. But they have more opportunities to do damage. More chances of success. And therefore the upper hand. Whilst the same holds true if they knock out/kill a party member.

And that is my understanding of the thinking behind that statement. Obviously there is a lot of mistakes above, and I’ve not explained bits enough. Put your corrections in the comments below.