Defending in Fate: Opposing opposed rolls

The Defend action logo from Fate CoreFate Core is a game about competent, proactive people leading dramatic lives. It’s a generic (that is, setting-free) system, which works because anything the characters might want to do can be regarded as one of four different actions: Attack, Defend, Overcome, and Create an advantage.

Personally, I think that’s one action too many.

A quick recap

For those not familiar, here’s a brief rundown of actions in Fate. Fate Core is available to download for free at the Evil Hat website, so if you need further detail on this, you should go and have a look at the actual rules.

All of the actions in Fate have the same mechanic:

  1. Roll four Fate dice (4dF in dice notation) – Fate dice, also called Fudge dice, are six-sided. There are two sides with plus signs (meaning +1), two sides that are blank (meaning 0), and two sides with minus signs (meaning ‑1).
  1. Add on modifiers – In Fate Core, modifiers include Skills (other versions of Fate might have other names for these, like FAE‘s Approaches), stunts (which may give characters bonuses when using some actions in certain situations), and invokes on aspects (which is really interesting, but beyond the scope of this post).
  1. Determine the outcome – Add up the dice result and the modifiers then compare the total to some target number. The difference determines the outcome: Failure, Tie, Success or Success with style. Success with style happens if you exceed the target by 3 or more.

So far so simple. So what is my problem with it?

(There is some maths involved in the rest of this post. You’ve been warned.)

The Defend action

Of the four actions in Fate, Defend is the only one you don’t do on your own turn. You do it on other people’s turns, in order to prevent them from using one of the other actions. It is an opposed roll, which means dice must have already hit the table for you to be attempting it.

Effectively, using Defend to react to another action means the original action works as follows:

  1. The acting player rolls 4dF and you roll 4dF to Defend. Because Fate dice produce probability distributions that are symmetrical around 0, it doesn’t matter whether you add the result together or subtract them. This is exactly the same as rolling 8dF.
  1. The acting player adds on their modifiers.
  1. Determine the outcome, using a target equal to the total of the Defender’s modifiers.

The only difference is in the first step.

That is, the only important difference between a standard action and an action opposed by Defend… is equivalent to making the active player roll 8dF instead of 4dF.

Probability distributions

Personally, I hate the phrase “more random”. Something is either random or it isn’t. Rolling 4dF is random. Rolling 8dF is random too. The difference is in the probability distributions.

Roll enough dice and you always get a probability distribution that is very close to the normal distribution, a bell curve. For Fate dice, that bell curve will always be centred on 0. But the more Fate dice you roll, the wider and flatter that curve will be.

It’s obvious that 8dF gives a result between ‑8 and +8, while 4dF can only be between ‑4 and +4, but as a result the chance of middling numbers is much lower. For example, the probability of getting a result from ‑1 to +1 is 62.96% on 4dF, but drops to 47.95% on 8dF. Have a look at the probability distributions:

A chart of probability distributions for 4 and 8 Fate dice

As a result, the dice result has a bigger swing, and larger numbers (either positive or negative) will crop up more often. At the same time, your Skills and other modifiers don’t change, so they have a proportionally smaller impact on the rolls. A peak Skill for a starting character in Fate Core is +4. That’s half of the spread of 4dF, but only a quarter of the spread of 8dF.

As a result, the random swing of the dice values has a bigger impact on rolls against “active opposition” than on rolls against “passive opposition”.

For a game that is supposed to be about competent, proactive people leading dramatic lives, I find it bizarre that the characters’ level of success depends less on their own abilities and more on dumb luck whenever someone is opposing them. Indeed, if they were truly leading dramatic lives (and not just active lives), I would think that the most important time for their own abilities to shine through is when they are being opposed by other people. Yet that doesn’t seem to be what Fate delivers.

The alternatives

There are plenty of ways around this problem. The simplest is to keep Defend as an action, but make it an action that does not use dice. Defend is already the odd one out, being the only action that doesn’t take place on the acting character’s turn. In this option, one character Attacks or Overcomes or Creates an advantage against a player character, and rolls 4dF as normal. The player character then Defends by working out what the target number is from their Skill, stunts, invokes and any other relevant elements… but they don’t roll dice. This is still different from passive opposition, but only because the narrative permissions for using Skills, stunts and invokes, etc. would be different for a passive character than an active one. And as an added bonus, we’ve sped up the flow of the game by removing an unnecessary dice roll.

But there are other options that could also be interesting to explore. If a group of players decides that they want success to depend more on dumb luck than inherent abilities, then consider using the above solution but making all actions work off 8dF instead of 4dF. Or, for that matter, consider a hack that uses any other number of Fate dice, depending on what balance you want between deterministic competence (fewer dice) or unpredictable luck (more dice). As long as the number of dice used in a game is consistent for every action, it shouldn’t otherwise affect the mechanics.

Or how about a hack that removes the Defend action entirely? Without a Defend action, only one side of any conflict would ever roll dice. Perhaps then the other actions can be made so that the side of the conflict that rolls dice will always be a player, and never the GM. This could allow the game to flow more like Dungeon World, or other games powered by the Apocalypse. Action could be tighter, faster, if perhaps more brutal. The idea intrigues me, but needs more work. I might come back to it in a future blog post.


5 thoughts on “Defending in Fate: Opposing opposed rolls

  1. Paul March 29, 2015 / 11:55 am

    This is interesting, and timely for me (I am currently reading Fate for the first time FOR REASONS, which is weird because I’ve said it is The Perfect Game repeatedly based on play alone).

    So, I think I agree with your intentions but disagree with your conclusion. One of the beauties of Fate is its simplicity. Paring down actions is key to that; consistency in dice mechanics also. Having two actions mathematically be a single, mechanically different action is awkward.

    But I do think there’s value in Defend, in that it gives players agency during the GM (or opposing player’s) turn. Now the solution you’ve outlined also achieves this, and is definitely worth exploring further.

    But aside from thinking about ‘players” ‘feelings’ I think that conflicts do actually need a wider probability distribution. If we’re assuming evenly matched opponents, using the 4Df distribution is almost never going to fill in that fourth stress box in a satisfying way (yes, having to fill in _something_ is cool, but can feel annoying and cheap). And the Severe Consequence is mathematically impossible to achieve.

    I don’t feel that wider distribution gets in the way of characters being “proactive, capable people leading dramatic lives” in conflicts. That would be true if the game specified _player_ characters, but it’s meant to be true of all characters in the game – everybody, on each side of the table, ought to be able to show off their abilities.

    I think you’ve identified an interesting inconsistency, but I think it’s there for some good reasons, and the designers have tried their best to hide it by framing it as two actions instead of one.

    I think.

    Liked by 1 person

  2. mpduxbury March 30, 2015 / 3:23 pm

    This is interesting. This is an interesting post about mathematical distribution in RPGs. My God.

    A pet peeve of mine is games that use different resolution mechanics for being challenging by the environment and being challenged by another character. Edgewalkers and Outbreak: Undead are particularly obnoxious – you want to roll high for PvP, and roll low for PvE. Fate is much better for at least using a consistent mechanic, but as you’ve outlined, the change is more impactful than it seems at first glance.

    The first thing to say is that Fate Core DOES advise you to not bother rolling for nameless NPCs, and just to use their flat value. I never follow this because… well, because I like rolling dice really (there are other, better reasons, but if I’m honest this is the main one). A logical extension of the rulebook’s stance would get you to the Apocalypse World/Numenera extreme of never, ever rolling, whereupon the 4dF vs 8dF quirk disappears entirely… except you still have to work out how to resolve player vs player :/

    To be honest, I’m never entirely clear where the line between “Active Opposition” (the unofficial fifth (re)action) and “Defend” is supposed to be. Which usually doesn’t matter, except when the defender succeeds with style. Or has a stunt that applies only for the Defend action.

    The other thing that occasionally troubles me is when a player rolls against Active Opposition (for example, Deceive vs Empathy to get away with a lie), and the character’s opposing skill is way lower than I would have set as a difficulty if it had been against Passive Opposition (for example, it’s a really preposterous lie). Active Opposition doesn’t have a modifier for difficulty. Fate isn’t too concerned with “realism”, so I should probably just ignore this problem – as it is, I usually just find some aspect to tag to reflect the increased challenge.

    Do you mind if I share this with the Fate G+ community?


    • Stephen March 30, 2015 / 3:34 pm

      I’ve already shared it at G+, and had some comments. Feel free to add your own thoughts over there.


      • mpduxbury March 30, 2015 / 4:00 pm

        Aha, just noticed it 🙂


  3. David April 1, 2015 / 9:49 am

    Here’s another option, PCs still roll Defend against an NPCs fixed attack value, then they feel their fate is in their own hands, plus players love rolling dice. PCs still Attack NPCs using their fixed Defend value. Move all the rolls to he Players side of the table.


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