The + 1 in Dungeon World is deceptively powerful! It is better than a + 2 in D&D and sometimes close to + 3. Just think about that when you design moves and such.
On 2d6, to get at least 7 = 58.33%, to get at least 10 = 16.67%. When you roll 2d6 + 1 your chances go up 13.89% to get a 7+ (to 72.22%) and 10.11% to get a 10+ (to 27.78%).
In D&D, obviously, each +1 increases your chance of hitting any number by 5%, since the curve is flat. So +2 is +10% and +3 is +15%.
I love me some probability. Good post.
Really good point. I feel that, especially in Dungeon World, lots of first draft custom moves grant a numerical bonus without taking into account how powerful it is.
Made this math some time ago. The important thing is that a -1 is powerful exactly as a +3
This is why magic items and custom moves are best created with fictional results as opposed to mechanical results.
thats what i calcualted:
-1=
< 6 = 58%
7-9 = 33,2%
10+ = 8,8%
+0=
< 6 = 41,4%
7-9 = 41,5%
10+ = 17,1%
+1=
< 6 = 27,6%
7-9 = 44,2%
10+ = 28,2%
+2=
< 6 = 16,5%
7-9 = 41,5%
10+ = 42%
+3=
< 6 = 8,2%
7-9 = 33,2%
10+ = 58,6%
Vincent Shine nicely done
And yet… any given +1 bonus only affects the outcome of a roll around 25% of the time.
That is, the +1 forward/ongoing only changes the outcome of the roll if your roll would have been a 6 or a 9. If your “base” modifier is -1, +0, +1, or +2 then you roll a 6 or a 9 only 25% of the time. (If the mod is -2 or +3, the chance of a 6 or 9 is 19.45%).
What that means is, a +1 bonus doesn’t feel like it makes a different very often. It can make you feel more confident before you roll. But after you roll, it’s pretty easy to see whether it did or didn’t affect the outcome. And usually, it did not.
As a result, I try to avoid writing (or taking) moves that require you to pay a cost (or take a risk) to get a +1 forward. It’s not a good gamble.
(Now, paying a cost or taking a risk to get +1 to roll after you’ve made it… that’s solid.)
This is the math based on the 36 different results you can have on 2d6:
Failure – Consequences – Success
Base 15/36 15/36 6/36
-1 21/36 12/36 3/36
+1 10/36 16/36 10/36
+3 3/36 12/36 21/36
Right. At +3 you are basically telling “competence porn” stories with a 92% chance of at least a 7 (see Vincent Shine’s calculations above) . That’s okay, so long as it is within focused bands of specialization. Your job as a DM is to diversify threats in a way that makes that competence not always relevant (but no so diverse that it’s never or seldom relevant.)
Probably the most likely problem is when you get someone achieving regular +3’s in Hack and Slash and wearing 3 armor. That figure is almost literally a tank. But you still aren’t powerless as a DM to make the game challenging for that person. For instance, give them a monster that has acid blood that eats through steel, ruining weapons and armor. I would force the attacker to Defy Danger Dex to avoid the blood acid splashes (-1 or -2 if the weapon has the messy tag) after each successful hit for damage with a piercing/cutting type weapon. And even then their weapon might be pitted and smoking by the end of the fight.
Soul Stigma made the primary point I was trying to communicate. In general I find “plus ones” a boring effect anyway. (And they can make the game boring if you aren’t careful.) I would rather see magical items with narrative effects. But weapons that do specific types of energy damage or get bonuses in specific situations can be really interesting with the right story behind them.
Ray Otus and specific types of damage, to me, are less mechanical and more fictional. Also items that are ordinary in most circumstances but magical in special circumstances can work well (such as a very ordinary dagger that has no special properties until used in a specific ritual).
DW really thrives on abstract mechanics and precise narrative.
Man, that’s worth repeating: “DW really thrives on abstract mechanics and precise narrative.”
I’d say “on going” and “forward” can make the difference on how OP a move can be.
Eric Lochstampfor true also.