Ability scores damage and bonuses/penalties

[Li Shenron]

I am thinking about introducing the general possibility for ability scores damage and bonuses or penalties to 5e.

These are my thoughts around the idea:

- effects that temporarily change your ability scores are fun, unless they cause many calculations (which was a big deal against ability score damage and changes in 3e/4e)
- in 5e there are less mathematical dependencies on ability scores than before, e.g. spell slots don't depend on you spellcasting ability score
- the 5e fixed Proficiency bonus makes it easy to calculate rolls on the fly most of the times (d20 + prof + ab.mod) so you don't have to edit your whole character sheet every time one of your ability scores changes
- allowing ability score changes during the game doesn't mean they have to happen often, in fact as a DM I plan to keep complete control of them (no standard options for the PC buff their abilities or damage those of others)

More precisely, my plan on using ability score changes is twofold:

- have the occasional magic item, curse/poison/disease, or special event cause a positive or negative temporary change to one ability score of a PC
- use ability score temporary damage to replace the death of a PC (for campaigns where we have agreed that the PC enjoy narrative protection from death)

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This House Rules actually doesn't need any other change in the game AFAIK. I can just drop a "you read the magic tome and feel inspired... your Charisma temporarily increases by 2" or "after being stung by the giant spider you start feeling week... your Strength temporarily decreases by 4", and that's it. No further rules changes are needed.

I am not worried about using the modified ability score/modifier for checks and rolls. The idea is that when you make a roll using that ability score, you calculate your bonus on the fly. Most of the times anyway the only modifier you need to add to the roll is the (current) ability score modifier itself, plus (or not) the Proficiency bonus.

However I have to make a checklist of "non-roll stuff" that still depends on ability scores, and then decide IF they should also be affected by the change to the associated ability score. And here is where I'd really like your opinions

Strength:
- speed reduction in heavy armor
- carrying capacity
- jumping range*

Dexterity:
- AC in light and medium armor

Constitution:
- hit points max

Int/Wis/Cha:
- spells DC*
- number of spells prepared

Those marked with * are not a big deal, they are technically not rolls but you need them only when you use them.

The rest is more complicated... I can decide that number of spells prepared is not affected by temporary scores, or at least today's spells prepared don't change.

But how about HPs, would you change them on the fly if Constitution changes or would you avoid complications and just keep them fixed?

And how about armor-related features and carrying capacity? I think I'd let Str and Dex changes affect them, but they do take some time to re-calc the effects...

 

[Li Shenron]

Forgot to mention that I only have the Basic game so far, where the only class feature that has constraints tied to an ability score is prepared spells.

I expect the PHB classes to have more features where especially the number of uses between rests is equal to an ability score modifier, and those are exactly what is difficult to handle when ability score changes, feel free to point out these instances.

 

[Sadrik]

I think these are workable additions. I also feel like the game is at a point where it can handle ability score changes without the maddening crunch of 3e. There are a couple of other things though that are more than calculation heavy. Attack roll, for both Dexterity and Strength. these often have more modifiers and it makes it simpler to not calculate them on the fly.

I would have liked to see ability score damage spread throughout the main rules (spells etc.). Keyed death to 0 CON, and several other effects keyed to 0 stats, paralysis 0 DEX etc. The game is simple enough to have these in there without an over-burdensome dependency based calculated character.

 

[Sadrik]

And to should it affect the following:

Strength:
- speed reduction in heavy armor yes
- carrying capacity yes
- jumping range* yes

Dexterity:
- AC in light and medium armor yes And more to point, I would do away with this dependency. Remove the dex caps. Lower heavy armor AC by 2 and medium by 1 and allow any dex to modify AC.

Constitution:
- hit points max no make this modifier only occur when leveling up. Makes things much easier.

Int/Wis/Cha:
- spells DC* no there is a math issue with this anyway. One way to tackle it is to remove the ability score from the equation, like 1e and 2e. So your spell's DC is 10 + prof and there save is d20 + stat or d20 + stat + prof. Fixes the high level issues.
- number of spells prepared no standardize it to 4 as if the character had an 18. basically decouple this dependency.

 

[Li Shenron]

Attack roll, for both Dexterity and Strength. these often have more modifiers and it makes it simpler to not calculate them on the fly.

Yes it might be... It can actually be simply left for each player to decide. For example, if playing a Fighter that often switches between different weapons and setup, and has fiddle bits from feats and class features, maybe it's best to have all options pre-calculated. OTOH most PCs IMXP have a favourite melee weapon and a favourite ranged weapon at most, and no special permanent bonuses, so for them it may not be so necessary to pre-calc.

I would instead always pre-calc the AC, at least because the starting point is already more complicated than the usual Proficiency + Ability Mod.

- AC in light and medium armor yes And more to point, I would do away with this dependency. Remove the dex caps. Lower heavy armor AC by 2 and medium by 1 and allow any dex to modify AC.
- spells DC* no there is a math issue with this anyway. One way to tackle it is to remove the ability score from the equation, like 1e and 2e. So your spell's DC is 10 + prof and there save is d20 + stat or d20 + stat + prof. Fixes the high level issues.
- number of spells prepared no standardize it to 4 as if the character had an 18. basically decouple this dependency.

These are a bit beyond the point of the thread, but all of them are interesting house rules!

I may remember wrong right now, but isn't Spell DC in 5e just 8 + Prof + Ability score? I don't see much problem in using the current (altered) Ability score on the fly, what is the 'math issue' in this case? It would have been much worse in 3e where spells of different levels had different DC, but this is no more.

 

[Sadrik]

The spell DC is that. But 10+prof without adding the stat fixes the "DC too high to save problem" high level 5e has.

To add a little more:
The DC range would be 12 - 16 instead of the potential 15 - 19

The problem is DC is scaling while most saves do not. So targeting a bad stat (with a stat of 8 say) they roll d20-1 vs DC 19. or even a good stat (stat 20) d20+5 vs DC 19, the game is set up so that the characters fail against saves at high level more than not. Even with proficiency and a high stat, where you might think they would almost have an auto save it is still d20+11 vs DC 19.

There are lots of potential fixes. I think the simplest one is to decouple the DC from the stat and go 10+Prof. So the numbers would be: worst scenario: d20-1 vs DC 16, or for the good ones d20+5 vs DC 16 and d20+11 vs DC 16. These mathematically fit my expectations better.