Thinking of a base mechanic: d20 + mod + boon/bane vs TN

[PhoenixPhyre]

I'm kinda noodling through an idea I had for a custom system and working on the core resolution mechanic.

Goals
1. Mostly flat curve. No dice pools. At most 2 dice. Why? Ease of use, mostly. I personally don't care for curved results very much.
2. Very bounded accuracy. All TNs between 5 and 20 and fairly insensitive to level/gear/etc. No stacking numeric modifiers or circumstance bonuses/maluses.
3. Simple and easy to use. Everything is either static or wrapped up in one "extra modifier".

System

Two types of rolls: Attacks and Tasks. No saves--going 4e style with everything directly harmful being an attack. Tasks are everything else.

6 Archetype Scores: Knowing, Perceptive, Precise, Strong, Tough, and Willful. (names not final). Range from 0 - 5. Set partially by class (which gives +2 to one and +1 to another), partially by lineage (granting a +1 to two different values, stacking), and partially by choice (another stacking +1). Over 10 levels you get +1 to two more. Weapons specify either STR or PRE for attacks; spells specify either KNO or PER for their attacks.

Both kinds of rolls are (1d20 + boost die) + Archetype Bonus >= TN. TN is one of (physical defense, magical defense) for attacks, or a fixed static value (range 10-20, with <10 being auto-success) for tasks.

Special thing here is the boost die--that includes all the effects of various things. By default, your boost die is 0. Each class gives training in two archetype that increases with level; this training basically sets your base boost die for any roll using that archetype. At higher levels, it also puts a floor -- at Master, you can't fail a TN 10 check. At Grandmaster (the highest), you can't fail a TN 12 check.

Other things may modify your boost die (applying Boost N / Bane N, which increases or decreases your boost die accordingly for all checks, so your actual boost die is your base for that archetype + the global modifier:

Boost level | Boost Die
-4 | -1d10
-3 | -1d8
-2 | -1d6
-1 | -1d4
0 | 0
+1 | +1d4
+2 | +1d6
+3 | +1d8
+4 | +1d10
+5 | +1d12

Damage for attacks is separate, but importantly "critical hits" (aka total on d20 + boost die > 20) for attacks do not increase damage, they impose conditions that affect the boost die (mostly).

That's it--everything revolves around modifying the boost die. Everything else is static at any given level.

The two defenses are set by your class and an archetype (Base + archetype, using TOU for physical and WIL for magical); armor acts as damage reduction not deflection.

Monsters do not make task rolls--instead they have features which modify the boost die (so a perceptive guard means you're making a Precise Task Roll against an environmental TN with bane N).

Training (applies to archetypes):
Hindered: Base boost is -1. If hindered by armor, cannot cast spells in armor.
Neutral (default): Base boost is 0.
Journeyman: Base boost is +1
Master: Base boost is +2, treat any total below 10 as 10.
Grandmaster: Base boost is +3, treat any total below 12 as 12.

Two questions:
1. Does this look sane? Are there obvious flaws here? Is this clunky? Have I described it anything like sensibly?
2. Are there systems that already do something somewhat similar (flat die + "modifier die") I can crib off of/gain inspiration from?

The VERY VERY VERY ROUGH draft of my initial thoughts here is in a google doc (https://docs.google.com/document/d/14PFKE3dTkMIjAvjZV91L7VG9OB9kopNZY14HAQ0BdI8/edit?usp=sharing) (CC-BY-SA 4.0 license (https://creativecommons.org/licenses/by-sa/4.0/legalcode))

[aimlessPolymath]

1. Does this look sane? Are there obvious flaws here? Is this clunky? Have I described it anything like sensibly?


The only thing that bothers me is that I don't love the combination of these two:

6 Archetype Scores: Knowing, Perceptive, Precise, Strong, Tough, and Willful. (names not final). Range from 0 - 5. Set partially by class (which gives +2 to one and +1 to another), partially by lineage (granting a +1 to two different values, stacking), and partially by choice (another stacking +1). Over 10 levels you get +1 to two more. Weapons specify either STR or PRE for attacks; spells specify either KNO or PER for their attacks.


Each class gives training in two archetype that increases with level; this training basically sets your base boost die for any roll using that archetype. At higher levels, it also puts a floor -- at Master, you can't fail a TN 10 check. At Grandmaster (the highest), you can't fail a TN 12 check.


Scaling both the boost die and the archetype bonus with level feels clunky- why not modify Archetype Scores instead of modifying the 'base' die? This would wrap up all 'static' and permanent bonuses to a roll in a single constant value, and clearly denote temporary, conditional, or situational values as operating by modifying the Boost die.

The current model also currently have edge effects at high levels- a Grandmaster doesn't benefit from gaining more than +2 bonuses to the boost die, while a Neutral character does.


2. Are there systems that already do something somewhat similar (flat die + "modifier die") I can crib off of/gain inspiration from?
The main comparison point I think of is banes and boons from Shadow of the Demon Lord (later adapted in Lancer and ICON)
If you have banes or boons, you roll that many d6 and take the highest value, then add or subtract that value from your roll. If you have banes and boons, they cancel each other out, one-to-one.
So two boons would be 1d20+Archetype Bonus+ 2d6kh1; three net banes would be 1d20+Archetype Bonus -3d6kh1.

This means that there are diminishing returns on stacking modifiers- you get a lot of gas out of your first boon, or out of canceling a boon to a bane, but there's less reason to chase down every situational modifier and achieve autosuccess.

[PhoenixPhyre]

The only thing that bothers me is that I don't love the combination of these two:

Scaling both the boost die and the archetype bonus with level feels clunky- why not modify Archetype Scores instead of modifying the 'base' die? This would wrap up all 'static' and permanent bonuses to a roll in a single constant value, and clearly denote temporary, conditional, or situational values as operating by modifying the Boost die.

The current model also currently have edge effects at high levels- a Grandmaster doesn't benefit from gaining more than +2 bonuses to the boost die, while a Neutral character does.


Yeah...the original idea was that the training would be more specific (kinda "skill-like"), so having them separate would represent bonuses to different things. But then I kinda moved away from that to a more "flat" idea...you're probably right. I'll keep the "floor" effect in the training part and remove the base boost from the training.



The main comparison point I think of is banes and boons from Shadow of the Demon Lord (later adapted in Lancer and ICON)
If you have banes or boons, you roll that many d6 and take the highest value, then add or subtract that value from your roll. If you have banes and boons, they cancel each other out, one-to-one.
So two boons would be 1d20+Archetype Bonus+ 2d6kh1; three net banes would be 1d20+Archetype Bonus -3d6kh1.

This means that there are diminishing returns on stacking modifiers- you get a lot of gas out of your first boon, or out of canceling a boon to a bane, but there's less reason to chase down every situational modifier and achieve autosuccess.

My issue with that is it means tracking all the individual sources. Although...now that I think about it, mine does as well to some degree. Hmm. Needs more thinking.

[aimlessPolymath]

My issue with that is it means tracking all the individual sources. Although...now that I think about it, mine does as well to some degree. Hmm. Needs more thinking.
It's essentially equivalent to this:

Boost level | Boost Die
-4 | -4d6kh1
-3 | -3d6kh1
-2 | -2d6kh1
-1 | -1d6kh1
0 | 0
+1 | +1d6kh1
+2 | +2d6kh1
+3 | +3d6kh1
+4 | +4d6kh1
+5 | +5d6kh1

Another way to limit modifier overload is to limit stacking- take Legends of Wulin, which uses static modifiers, but you only apply the highest positive and lowest negative modifier for any given roll. PF2e has a similar rule for status/item/circumstance bonuses, taking the highest magnitude bonus and penalty for each modifier type (and there are only those three types of modifiers).

[PhoenixPhyre]

Another way to limit modifier overload is to limit stacking- take Legends of Wulin, which uses static modifiers, but you only apply the highest positive and lowest negative modifier for any given roll. PF2e has a similar rule for status/item/circumstance bonuses, taking the highest magnitude bonus and penalty for each modifier type (and there are only those three types of modifiers).

I think this is more the way I'd go. So if you had

Boost 1,
Bane 4,
Boost 5,

you'd actually have (-4 + 5) = +1 (ie 1d4). And adding any number of additional boosts/banes wouldn't change anything. But if you only had Boost 1 and got Boost 2, you'd now have Boost 2, not 3.

[Thane of Fife]

2. Are there systems that already do something somewhat similar (flat die + "modifier die") I can crib off of/gain inspiration from?


Alternity is kind of similar, though it's a roll low system. So, for example, you have a Shooting skill of 14 and roll a d20 against that, using some kind of "Situation Die" as a modifier based on how hard the situation is. Alternity also has degrees of success if you roll sufficiently far below the skill.