D&D 5E My theory on 5e's core mechanic

[Falling Icicle]

I believe it will be a d20 based opposed roll system focused on stats. Except instead of the +1 for every two points above 10, I think for every point above 10, you will get +1 to your roll. Thus the designer's comment about a races and classes getting a +1 to your stat makes more sense to me.

Another way to look at things is a STR of 16 means you are essentially taking 10 on a STR check with a +6 bonus. So now designer comments on comparing your STR to the break DC of a door and letting you break it without bothering to roll, or letting a guy with STR 15 automatically succeed on jumping a pit, make more sense. Your stat score is for all intents and purposes the same as a passive score in 4e parlance.

I suggested having ability scores give a +1 bonus per point above 10 in another thread about odd-numbered ability scores, though the idea of your total score being the same as a "passive" score (i.e. taking 10) had not occurred to me, and sounds very intuitive and simple. Good analysis. I think you may be right, and if so, I would very much approve of this system.

For example, instead of having AC be 10 + Dex modifier + armor + shield, it would just be Dexterity score + armor + shield. Easy. It also makes the ability scores ranging from 3-18 make sense again. For a long time, I've wondered why they even kept them when you only really used the modifiers instead of the actual score. Now, there's a point to it. I like it.

I hope that the people at WotC read this, because if this isn't 5'e core mechanic, it definitely deserves consideration!

 

[Chris_Nightwing]

I thought it would be useful to consider opposed rolls under this proposed system. At first I was skeptical - stat scores on the standard array vary from 10 to 16 and having a +6 bonus on a d20 roll sounds like an amazing advantage - however the curve is more subtle than I first thought:

Relative Bonus / % Win
------------------------------
-20 / 0.000
-19 / 0.125
-18 / 0.500
-17 / 1.125
-16 / 2.000
-15 / 3.125
-14 / 4.500
-13 / 6.125
-12 / 8.000
-11 / 10.125
-10 / 12.500
-9 / 15.125
-8 / 18.000
-7 / 21.125
-6 / 24.500
-5 / 28.125
-4 / 32.000
-3 / 36.125
-2 / 40.500
-1 / 45.125
0 / 50.000
+1 / 54.875
+2 / 59.500
+3 / 63.875
+4 / 68.000
+5 / 71.875
+6 / 75.500
+7 / 78.875
+8 / 82.000
+9 / 84.875
+10 / 87.500
+11 / 89.875
+12 / 92.000
+13 / 93.875
+14 / 95.500
+15 / 96.875
+16 / 98.000
+17 / 98.875
+18 / 99.500
+19 / 99.875
+20 / 100.000

I assumed that a tie resulted in a roll-off, with a 50% chance of winning.

It turns out to be a nice cumulative binomial. Now, whether you like this or not depends on whether you think that small advantages should be more significant than large advantages. I like this because it encapsulates the law of diminishing returns - each +1 you accumulate is worth less and less when you are superior, and more and more when you are inferior.

 

[Number48]

My thought/preference is that there are on derived modifiers from ability scores. You add the entire ability score. Otherwise, the number itself is meaningless, as it was meaningless in 3E and 4E. In 3E and 4E, your ability score might as well be 2 instead of 14, because you will use the 2 and never the 14. So, if you add the entire score, the odds stay exactly the same as Dragonblade demonstrated.

The other effect, however, of having no modifiers is that attacks become skill rolls because they are functionally identical, and there is no such thing as bonus damage from ability scores. Now THAT will encourage people to not have a prime stat and 5 dump stats.

I think the simple way for the layman to think about how to determine how much to pump into a single score is to ask yourself, how often am I going to roll far above what I need to hit? The most optimal solution is if you always roll the exact number you need, that you aren't "wasting" bigger number. Now, obviously that is impossible. But, if you are regularly getting 10 more on the dice than the target number in your highest stat, you've put too much into that stat, and are probably failing on your other stat rolls more often as a consequence.

 

[Falling Icicle]

My thought/preference is that there are on derived modifiers from ability scores. You add the entire ability score. Otherwise, the number itself is meaningless, as it was meaningless in 3E and 4E. In 3E and 4E, your ability score might as well be 2 instead of 14, because you will use the 2 and never the 14. So, if you add the entire score, the odds stay exactly the same as Dragonblade demonstrated.

The total ability score isn't meaningless if it is used as the "passive" score (similar to taking 10). For example, the fighter has a 17 Str and is trying to break down the door. The DM determines that the DC is 15 to break down that door, so he let's the fighter do so without rolling. Likewise, Dexterity + Armor is easier than 10 + Dexterity modifier + Armor. Your Wisdom score, likewise, could be used as your "Passive Perception."

 

[Number48]

True. I just see deriving a bonus from a stat as an unnecessary step. We need less total numbers to look at, not more.

 

[Nebulous]

i think you might be onto something here, Dragonblade. I hope 5e does indeed go this direction.

 

[Izumi]

It's an interesting idea, but the extra die roll slows down play, and really doesn't provide more verisimilitude when hp already includes blocks, deflections, and evasions within it's abstraction. An interesting interpretation might be to think of a d20 attack roll as timing to reach impact velocity on targeted area, BAB as skilled accuracy, a Str mod as faster power to reach velocity in a shorter time, AC as only bypassed by a well timed strike to a vulnerable area, and the damage roll is the percussion impact radominzed by targets motion at impact, speed at impact, absorption of impact, or evasion attempt etc. Math's not my strong suit, but two people of equal skill in the same armor should not be at 50/50. They should be at 33.3/33.3 with a mutual hit at 33.3. Two untrained people wearing chainmail would need a 15 or better to reach the upper 33.3% (since 16 is 35%) and score a hit on AC 5. Our Wargamer Forefathers Dave and Gary knew what they were doing, I think. I sure hope Archmagus Monte, and Baelnorn Bruce didn't go with OPs theory. It does have some charming balance though, and it made me think.

 

[Gundark]

You could eliminate a lot of the rolling as by using stats. Need to jump up on the table? That would be a DC 10. If your strength (or dex) is 10 or greater you succeed no roll needed. The fighter wearing heavy armour? The DC is adjusted to 15. Is your stat less than the DC? Then you roll.

 

[Astrosicebear]

Awesome post, and replies.

I do think the designers already said that there are DCs, so opposed rolls for most things seems to not be available. And since they were running a B2 adventure, I am pretty sure, as someone else noted, they were taking THAC0 and just inverting it. THAC07 became AC 13, or something simple.

The designers have also said, as noted, that Stats will play a direct role in lowering modifiers and applying to skills. So I do expect to see a STR 16 without +3, and possibly have a breakdown of every 5 points above 10 is a modifier instead of 2 (and possibly reverse for penalties). With this setup you can curve the power creep of inherent bonuses and apply that mentality to the designers goals of making monsters viable at most levels. If the Orc at level 1 has an AC of 16 and your average Fighter say, with a STR 16 has a bonus of +2 from stat, +1 from race(say hes half orc), and +1 from fighter type bonus or weapon type bonus, that's a +4. If that same 30th level fighter has a STR of 24 now (+3), a race bonus of +1, and a class bonus (lets guess at +1 per 5 class levels) +6, totaling +10, that AC 16 is still very viable.

All speculation of course, but I foresee stats that are +25 to be considered 'epic'.

 

[Dragonblade]

Having given it this additional thought, I suppose I need to modify the conclusion of my earlier post. Opposed rolls introduce some interesting tensions:
1) The greater returns for small changes in mid-range ability scores compared to those at either extreme will tend to incentivize players to keep the middle ground.
2) Despite this, decreasing an infrequently used low stat to increase a frequently used high stat on a 1-for-1 basis will be a favorable trade.
3) In any case, large disparities in scores have less impact than they would in 3.5/4e.

These suggest to me that opposed checks may tolerate min/maxing (and other wide disparities) more so than actively discourage it. For games with rolled stats that is a clear win. For point-buy games #2 suggests that some escalating cost for higher scores will still be needed.

Oof, for a quibble that took a bit more effort than I intended.

Good stuff, Ainamacar!

I'm about 12 years removed from college and all my calc, statistics, and probability classes, so thanks for putting it together better than I could. It was your other post about the probabilities of a d20 opposed roll system that really crystallized a lot of thoughts in my head.