D&D 5E How do Ability Score Modifiers Stack?

[LordEntrails]

So how do various ability score modifiers stack? Especially when one modifier sets a score at a set value and another modifiers the score by a set amount.

The specific case, rogue (Strength 11) gets hit a couple of times by a Shadow Assassin (DoMM) and loses 10 points of strength. So now their strength is 1, all is good. But after running to cover, the rogue applies Demonic Jelly (WDDH) which sets their strength score to 21 (i.e. like a potion of giant strength). Is the rogues strength now 21 because of 'order of operations', i.e. does it matter in which order the magical modifiers apply? And therefore if they had used the Jelly first their strength would be 11 (21-10)?

Other cases I'm missing or should consider?

 

[CleverNickName]

Works with a potion but would get weird with a magic item. Say you have a ring that sets an attribute to X. Having players take off the ring to lose the benefit and then put it on again to gain the benefit would be weird.

"Have you tried taking it off and on again?"

This hasn't really been an issue.

We have a character who wears a set of Gauntlets of Ogre Power, which makes their Strength score 19 while they are attuned.

If they drink a Potion of Storm Giant Strength, there are two ways to rule it: either their Strength becomes 29 and the gauntlets have no effect, or their Strength stays 19 and the potion has no effect. You might rule differently, but I rule for the first option because (1) it's more awesome, and (2) because the description of those gauntlets specifies what happens if your Strength is higher than 19.

The real benefit of Gauntlets of Ogre Power isn't the 19 to Strength...it's never having to worry about shadows.

 

[Yora]

You might rule differently, but I rule for the first option because (1) it's more awesome

Which is again the paradigm of "whichever is in the character's favor".

 

[CleverNickName]

Which is again the paradigm of "whichever is in the character's favor".

Eh, not always. I'm the DM, so it's more about "whichever tells the better story."

But the story is usually about the characters, so...yeah.

 

[LordEntrails]

Wasn't there a rule of thumb of "whichever order is most beneficial to the character"?

Not that I've ever heard of. There is the rule of Cool though which is similar.
But one rule I do stick with is that if it works one way for the PCs, then it works the same way for the NPCs/creatures. And same in reverse. I would never have magic work one way for the benefit of the players, and then if used by adversaries have it work a different way just so the players once again get the benefit.

Honestly the real answer is "Don't sweat the small stuff". Either way works, either way rewards the PCs for using the item, and either way ends at the end of the next short rest. Make a decision and move on; time spent faffing and looking things up in the book to work out what the "right" answer is is bad and time spent actively arguing is worse. I'd give the players the advantage here as the DM; the difference isn't much and tehy get to feel cooler.

I don't get caught up during a session, I go with a ruling on the spot. But sometimes either the session ends at a convenient time (like this one did, combat is over, but effects are still in play) or I think it may be likely a situation like this comes up again I put some more thought into it. And occasionally reach out to see what folks here think.
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It sounds like so far, no one has found any rule references or Sage or JC tweets on this or a similar issue?

 

[LordEntrails]

I'd say set value is set value, modifiers are ignored.

Doesn't work for me. Take the example of Gauntlets of Ogre Strength, with your ruling, a character wearing those would never be effected by a strength drain. That would be uninteresting to me, plus make such magic items even more powerful than they already are.