That conclusion doesn't sit well with me, because it requires us to throw out an assumption we had all agreed on earlier: that you resolve advantage to get your initial result and then silvery barbs comes in response to that to change the result from what it was before. If you instead use the reroll to "turn back the clock" and plug the rerolled d20 into the original process, then you have to include all aspects of that original process, including advantage. And then we go back to the problem at the very beginning of this thread: How do I reroll a single d20 in an advantage situation?
You could just say it's easy. You apply everything except for advantage. But there is nothing in the spell's description or in the general rules that says you apply everything except advantage. It only works if you take advantage out of the equation by resolving it before applying the silvery barbs reroll--not when you plug it back into the original attack and play it forward from that point. If you are playing it forward from the original attack roll, then the attack already has advantage. If it's a new roll, then it doesn't have advantage from the original roll, and that should allow you to apply advantage to the reroll. Either way, you end up with advantage on the reroll.
And that brings us back to the old question, but with a new twist. If you reroll an attack roll, is the new roll and attack roll? Or is the new roll something unique and different? And now... is the new roll actually just the old attack roll, but with a different number?
That conclusion doesn't sit well with me, because it requires us to throw out an assumption we had all agreed on earlier: that you resolve advantage to get your initial result and then silvery barbs comes in response to that to change the result from what it was before. If you instead use the reroll to "turn back the clock" and plug the rerolled d20 into the original process, then you have to include all aspects of that original process, including advantage. And then we go back to the problem at the very beginning of this thread: How do I reroll a single d20 in an advantage situation?
What the advantage mechanic does is select which die you use. That's the one you re-roll, the one that advantage selected for the check. The other die was discarded and no longer factors into the equation. If you just re-roll the entire check, which as far as I can tell has been what you've been suggesting, I see no reason why you wouldn't still have advantage or disadvantage if you did initially.
You could just say it's easy. You apply everything except for advantage. But there is nothing in the spell's description or in the general rules that says you apply everything except advantage. It only works if you take advantage out of the equation by resolving it before applying the silvery barbs reroll--not when you plug it back into the original attack and play it forward from that point. If you are playing it forward from the original attack roll, then the attack already has advantage. If it's a new roll, then it doesn't have advantage from the original roll, and that should allow you to apply advantage to the reroll. Either way, you end up with advantage on the reroll.
There's nothing in the spell's description that says you apply anything except for the single d20 that's being factored into the total, which is what I've been saying.
And that brings us back to the old question, but with a new twist. If you reroll an attack roll, is the new roll and attack roll? Or is the new roll something unique and different? And now... is the new roll actually just the old attack roll, but with a different number?
If you re-roll an attack roll, then yeah, the new roll is an attack roll. I'm not aware of any feature that lets you do that though. And I'd say it's the same attack roll with a different number, but not only am I not aware of any feature for which that would make a difference, I'm pretty confident there is no such feature :p
No, it's not. It is quite obvious that they are two different things. But, if that doesn't convince you, I hope this does: The rule tells you that you must reroll the d20 and use the lower roll. How do you want to reroll that dice with advantage? It doesn't make sense. You take the die and roll it again. There is no possible advantage or disadvantage here.
It isn't obvious to me. In fact, that seems counterintuitive to me. I have laid out some things that an attack reroll shares with an attack roll. Can you tell me some things about how an attack reroll works that are different from an attack roll?
To answer your second question, I see it as a nested operation. Let's say someone gives you advantage on your initial attack roll because of the help action. To get your initial result, you resolve advantage, but you still end up with one single result, right? Let's call that result R1. Then you apply silvery barbs to that result to force it to be rerolled. Let's call the reroll R2. So silvery barbs forces you to make R2 and compare it to R1 and take the lower of the two. If you use DM inspiration to give yourself advantage on R2, you still end up with a single result for R2. Then you compare that to R1 and take the lower of the two.
Let me pose my position differently. Let's say I was under the benefit of the bless spell. I get to add 1d4 to my attack rolls. If silvery barbs forced me to reroll my attack, would you still let me add 1d4 to the reroll? If the answer is, "No, because the reroll is not an attack roll" then why should I be able to add my attack bonus to it? Surely you wouldn't deny me that on the reroll, right?
With respect, but I think you are messing things up a lot and making them more difficult than they are. Silvery Barbas forces you to repeat a D20 and take the worst. Simply that. You're not attacking (or saving, or whatever) again. You're just taking one D20 (usually the only one you've rolled on your attack, saving, or whatever), and rolling it again. It's okay to twist the rules, and try to find holes in the system. But what you are proposing just doesn't make sense. What is the point of rerolling a single D20 with advantage? By concept, it's impossible.
Can the silvery barbs spell in Strixhaven affect Legendary Resistance? No. When a creature uses Legendary Resistance, the creature turns a failed saving throw into a success, regardless of the number rolled on the d20. Forcing that creature to reroll the d20 afterward doesn’t change the fact that the save succeeded as a result of Legendary Resistance. No amount of rerolling will undo that success.
Can the silvery barbs spell in Strixhaven affect Legendary Resistance? No. When a creature uses Legendary Resistance, the creature turns a failed saving throw into a success, regardless of the number rolled on the d20. Forcing that creature to reroll the d20 afterward doesn’t change the fact that the save succeeded as a result of Legendary Resistance. No amount of rerolling will undo that success.
Good to know that the obvious answer was the correct one. xD
For my part, I think it is meant to work like halfling luck, and we can take guidance from the description of advantage in the PHB: When you have advantage or disadvantage and something in the game, such as the halfling's Lucky trait, lets you reroll or replace the d20, you can reroll or replace only one of the dice. You choose which one. For example, if a halfling has advantage or disadvantage on an ability check and rolls a 1 and a 13, the halfling could use the Lucky trait to reroll the 1.
This is correct. It is a reroll of ad20. Nothing more. The wording on applying the result in the Silvery Barbs spell is very similar to the wording in the Halfling Lucky Trait. It would work exactly the same way as the Lucy trait, you replace one of the dice.
Lucky Trait: When you roll a 1 on the d20 for an attack roll, ability check, or saving throw, you can reroll the die and must use the new roll.
Silvery Barbs: You magically distract the triggering creature and turn its momentary uncertainty into encouragement for another creature. The triggering creature mustreroll the d20 anduse the lower roll.
That conclusion doesn't sit well with me, because it requires us to throw out an assumption we had all agreed on earlier: that you resolve advantage to get your initial result and then silvery barbs comes in response to that to change the result from what it was before.
You could just say it's easy. You apply everything except for advantage. But there is nothing in the spell's description or in the general rules that says you apply everything except advantage. It only works if you take advantage out of the equation by resolving it before applying the silvery barbs reroll--not when you plug it back into the original attack and play it forward from that point. If you are playing it forward from the original attack roll, then the attack already has advantage. If it's a new roll, then it doesn't have advantage from the original roll, and that should allow you to apply advantage to the reroll. Either way, you end up with advantage on the reroll.
And that brings us back to the old question, but with a new twist. If you reroll an attack roll, is the new roll and attack roll? Or is the new roll something unique and different? And now... is the new roll actually just the old attack roll, but with a different number?
I realize I may have missed something in the first 4 pages, but while your assumption may be logical, it is not consistent with the specific rule on doing a reroll with advantage or disadvantage (posted by the OP). The rules are pretty clear on this.
When we start talking about "turning back the clock" and "is the new roll something different" you are putting up logical constructs outside of the bounds of the actual RAW. This is not appropriate, because it is a game focused applying a ruleset and dice to describe a story. If we are going to do this, you can actually get yourself into a paradox - he made the attack with advantage, so I use my reaction now the attack is not successful, so then that means I never had the chance to use the reaction, so we go back to the original result, that is a hit so I use my reaction .....
Bottom line - you made him reroll a d20 with the general wording of the SB spell. The specific wording on rerolling a d20 with advantage or disadvantage tells you exactly what to do in this case, replace one of the dice. The general wording in the SB description tells you how that replacement works - you use the lower of the original or the new roll as the replacement. Whatever the other dice was remains the same and the outcome depends on the results of both dice.
What the advantage mechanic does is select which die you use. That's the one you re-roll, the one that advantage selected for the check. The other die was discarded and no longer factors into the equation. If you just re-roll the entire check, which as far as I can tell has been what you've been suggesting, I see no reason why you wouldn't still have advantage or disadvantage if you did initially.
The other dice in advantage is not discarded unelss it is lower than your Silvery Barbs reroll. If it is higher it is the Silvery Barbs dice that is discarded.
The PHB specific rules on applying a d20 reroll with advantage are pretty clear on this. It effects only one dice. If you roll a 19 and an 10 and someone casts silvery barbs then you reroll the 19. If you get a 20 on the reroll the result of the attack is 19, if you get a 15 the result of the attack is 15, if you get a 4 the result of the attack is a 10.
If the attack was with disadvantage instead of advantage and made the same rolls, the result would be a 10, 10 and 4 respectively.
What the advantage mechanic does is select which die you use. That's the one you re-roll, the one that advantage selected for the check. The other die was discarded and no longer factors into the equation. If you just re-roll the entire check, which as far as I can tell has been what you've been suggesting, I see no reason why you wouldn't still have advantage or disadvantage if you did initially.
The other dice in advantage is not discarded unelss it is lower than your Silvery Barbs reroll. If it is higher it is the Silvery Barbs dice that is discarded.
The PHB specific rules on applying a d20 reroll with advantage are pretty clear on this. It effects only one dice. If you roll a 19 and an 10 and someone casts silvery barbs then you reroll the 19. If you get a 20 on the reroll the result of the attack is 19, if you get a 15 the result of the attack is 15, if you get a 4 the result of the attack is a 10.
If the attack was with disadvantage instead of advantage and made the same rolls, the result would be a 10, 10 and 4 respectively.
The PHB's rules on d20 rerolls are only valid prior to employing the advantage/disadvantage mechanic. The other die is discarded by that mechanic, not by the spell, and it's only after that that Silvery Barbs can even be cast.
You'd be correct if the trigger for the spell were "when a creature you can see within 60 feet of yourself makes an attack roll, an ability check, or a saving throw," but it's not, so you're not. The trigger is when a creature succeeds. A creature cannot succeed until the two dice of advantage/disadvantage have been collapsed into one.
For my part, I think it is meant to work like halfling luck, and we can take guidance from the description of advantage in the PHB: When you have advantage or disadvantage and something in the game, such as the halfling's Lucky trait, lets you reroll or replace the d20, you can reroll or replace only one of the dice. You choose which one. For example, if a halfling has advantage or disadvantage on an ability check and rolls a 1 and a 13, the halfling could use the Lucky trait to reroll the 1.
This is correct. It is a reroll of ad20. Nothing more. The wording on applying the result in the Silvery Barbs spell is very similar to the wording in the Halfling Lucky Trait. It would work exactly the same way as the Lucy trait, you replace one of the dice.
Lucky Trait: When you roll a 1 on the d20 for an attack roll, ability check, or saving throw, you can reroll the die and must use the new roll.
Silvery Barbs: You magically distract the triggering creature and turn its momentary uncertainty into encouragement for another creature. The triggering creature mustreroll the d20 anduse the lower roll.
To follow up, this is incorrect, because the trigger for Lucky is "When you roll a 1," and the trigger for Silvery Barbs is "when a creature succeeds." These wordings are extremely different.
The PHB's rules on d20 rerolls are only valid prior to employing the advantage/disadvantage mechanic. The other die is discarded by that mechanic, not by the spell, and it's only after that that Silvery Barbs can even be cast.
No they aren't. As a matter of fact the example used is the Halflings Lucky trait which states explicitly that you "must use the new roll" in the exact same syntax as Silvery Barbs where it says you "must use the lower roll"
They are the same.
You'd be correct if the trigger for the spell were "when a creature you can see within 60 feet of yourself makes an attack roll, an ability check, or a saving throw," but it's not, so you're not. The trigger is when a creature succeeds. A creature cannot succeed until the two dice of advantage/disadvantage have been collapsed into one.
This is just the casting time, it has nothing to do with how you execute the reroll itself and is not reflected in the text of the spell description. This is similar to the wording in other things "before you know the result" or "after you know the result" used elsewhere.
A reroll can change sucess or failure in any time it is used. That is not unique to Silvery Barbs, in fact that is the whole idea of the reroll. Nothing in Silvery Barbs says or even suggests that the rules for executing a reroll with advantage or disadvantage are any different for this spell as other abilities that cause a reroll.
To follow up, this is incorrect, because the trigger for Lucky is "When you roll a 1," and the trigger for Silvery Barbs is "when a creature succeeds." These wordings are extremely different.
That only thing that is differnet is how it is triggered. In either case it is a reroll and specific beats general. You are replacing one d20 with another d20 and the specific rules for applying a reroll to advantage or disadvantage override the general rules on how the Lucky Trait or the Silvery Barbs spell affect the outcome of the Save, Ability Check or Attack.
What triggers it is irrelevant to this discussion.
What triggers it is irrelevant to this discussion.
What triggers it is the only thing that's relevant to this discussion. What triggers it determines whether there's one die to re-roll or there are two. If you can't get behind that fundamental premise, there's no productive discussion to be had.
What triggers it is irrelevant to this discussion.
What triggers it is the only thing that's relevant to this discussion. What triggers it determines whether there's one die to re-roll or there are two. If you can't get behind that fundamental premise, there's no productive discussion to be had.
No it doesn't, the rules on executing a reroll with advantage or disadvantage rolls say nothing at all about the trigger event affecting that, it says "When you have advantage or disadvantage and something in the game ...let's you reroll the d20 you can reroll only one of the dice"
Ask yourself the question - is SB "something in the game that let's you reroll the d20"? Answer yes it is absolutely, so this specific rule on advantage and disadvantage applies to the general way you do the reroll in SB.
If this was not a "reroll" you could be right. You would have a point if for example the description said the player who casts SB rolls a dice when the enemy makes save/ability/attack (similar to the lucky feat when you change an enemy roll or with portent which happens before the enemy rolls at all). If it used this wording instead of the enemy "rerolls the d20" I could see a different reading. But this is a d20 reroll specifically and there is a clear and specific way to apply a reroll with advantage or disadvantage.
If you really think this is not the correct interpretation, please point to the rule that says or even suggests you handle a reroll differently based on what triggers it. Where does it say in the rules that "what triggers it determines whether there's one die to re-roll or there are two".
What triggers it is irrelevant to this discussion.
What triggers it is the only thing that's relevant to this discussion. What triggers it determines whether there's one die to re-roll or there are two. If you can't get behind that fundamental premise, there's no productive discussion to be had.
No it doesn't, the rules on executing a reroll with advantage or disadvantage rolls say nothing at all about the trigger event affecting that, it says "When you have advantage or disadvantage and something in the game ...let's you reroll the d20 you can reroll only one of the dice"
Ask yourself the question - is SB "something in the game that let's you reroll the d20"? Answer yes it is absolutely, so this specific rule on advantage and disadvantage applies to the general way you do the reroll in SB.
If this was not a "reroll" you could be right. You would have a point if for example the description said the player who casts SB rolls a dice when the enemy makes save/ability/attack (similar to the lucky feat when you change an enemy roll or with portent which happens before the enemy rolls at all). If it used this wording instead of the enemy "rerolls the d20" I could see a different reading. But this is a d20 reroll specifically and there is a clear and specific way to apply a reroll with advantage or disadvantage.
If you really think this is not the correct interpretation, please point to the rule that says or even suggests you handle a reroll differently based on what triggers it. Where does it say in the rules that "what triggers it determines whether there's one die to re-roll or there are two".
Silvery Barbs is used when the roll has succeeded, this means you have to determine whether the roll has succeeded or not. This is the trigger and is, therefore, one of the most important parts of Silvery Barbs.
With Advantage and Disadvantage this means determining which die of the two rolled is used and figuring out whether the roll was a success or a failure. Once you have determined that the roll succeeded then Silvery Barbs can be cast. At this point the only dice that matter are the one from Advantage/Disadvantage that resulted in the success and is being re-rolled and the new D20 introduced by the re-roll.
If both dice from Advantage/Disadvantage had failed then Silvery Barbs would not be able to be cast. Ergo the lowest die of the two is irrelevant and, since you must discard the lowest through the process of determining success or failure, is discarded.
Silvery Barbs is used when the roll has succeeded, this means you have to determine whether the roll has succeeded or not. This is the trigger and is, therefore, one of the most important parts of Silvery Barbs.
Sure that is what triggers the reaction, but once the trigger happens that has no longer "suceeded" and you determine success the same way as with any other reroll. If we are not going to apply advantage and disadvantage to the reroll in the normal specific fashion, why would we apply AC and attack bonus to it in the normal fashion? After all it already suceeded, the AC and attack bonus don't matter.
This idea that the "sucess" is now in concrete is just foolish and taken to its logical conclusion then the Silvery Barbs will have no effect on it at all. Taking this logic; Silvery Barbs does not actually say the enemy fails if the new roll of it is lower than the threshold for sucess, It just says you "use the lower roll".
What do you use it for? You obviously use it to figure out if it is a failure or a success in the normal manner of applying dice. If this is a success that can't be changed because it already happenened then SB is worthless. I roll a 20, you use silvery barbs and I reroll a 1. I say still hit you with a crit because the hit was already a success before you cast Silvery Barbs, sure I "use the new d20", I guess I use it to look at, but the hit was already a sucess and if it wasn't you could not have cast SB in the first place. We do not go through the perscribed process of redetermining if it is a success because it already is a success, it would not have triggered SB if it wasn't.
After all it is already a success right?
That is not how the spell is supposed to work. When you roll the reroll a dice you use it to replace the other dice and then figure out sucess or failure based on the new result. When you do this with advantage or disadvantage you replace one of the dice. The rules are clear and no one has presented any part of the rules that suggest this case works any different.
With Advantage and Disadvantage this means determining which die of the two rolled is used and figuring out whether the roll was a success or a failure. Once you have determined that the roll succeeded then Silvery Barbs can be cast. At this point the only dice that matter are the one from Advantage/Disadvantage that resulted in the success and is being re-rolled and the new D20 introduced by the re-roll.
Why would the other dice not matter? What part of the rules suggest this? Where does it say you do not use two dice for determining the results of advantage/disadvantage after triggering a reaction with a success?
Nothing in the Silvery Barbs description says this. So far no one has shown anything in the rules that support this interpretation.
The only thing the sucess does is trigger the reaction used for the casting time. That is the only place "success" it is even mentioned in the spell.
If both dice from Advantage/Disadvantage had failed then Silvery Barbs would not be able to be cast. Ergo the lowest die of the two is irrelevant and, since you must discard the lowest through the process of determining success or failure, is discarded.
The PHB does it say the lower dice is "discarded". Where do you get that "you must discard the lower dice"?
People keep using that term "discarded" in the thread, but that is not RAW. The rules say you "use the higher of the two rolls if you have advantage". They never say to throw out or discard the lower roll and certainly don't use "must" as a qualifier for that.
Sure, if you roll below the threshold on both you fail and you don't trigger the spell. If you did not cast the spell then you don't replace any dice. It does not even matter if it is in your spell book, it is irrelevant to the discussion.
The method for resolving success/failure is the same whether you cast SB or not. The only difference is one dice can potentially change.
For what it's worth, the interaction between SB and advantage is pretty well settled by this point. SB doesn't have any wording concerning advantage or disadvantage because it doesn't care about the process that leads to the result--only the result itself.
Rollback Post to RevisionRollBack
"Not all those who wander are lost"
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OK, that's MUCH more logically reasonable :)
That conclusion doesn't sit well with me, because it requires us to throw out an assumption we had all agreed on earlier: that you resolve advantage to get your initial result and then silvery barbs comes in response to that to change the result from what it was before. If you instead use the reroll to "turn back the clock" and plug the rerolled d20 into the original process, then you have to include all aspects of that original process, including advantage. And then we go back to the problem at the very beginning of this thread: How do I reroll a single d20 in an advantage situation?
You could just say it's easy. You apply everything except for advantage. But there is nothing in the spell's description or in the general rules that says you apply everything except advantage. It only works if you take advantage out of the equation by resolving it before applying the silvery barbs reroll--not when you plug it back into the original attack and play it forward from that point. If you are playing it forward from the original attack roll, then the attack already has advantage. If it's a new roll, then it doesn't have advantage from the original roll, and that should allow you to apply advantage to the reroll. Either way, you end up with advantage on the reroll.
And that brings us back to the old question, but with a new twist. If you reroll an attack roll, is the new roll and attack roll? Or is the new roll something unique and different? And now... is the new roll actually just the old attack roll, but with a different number?
"Not all those who wander are lost"
What the advantage mechanic does is select which die you use. That's the one you re-roll, the one that advantage selected for the check. The other die was discarded and no longer factors into the equation. If you just re-roll the entire check, which as far as I can tell has been what you've been suggesting, I see no reason why you wouldn't still have advantage or disadvantage if you did initially.
There's nothing in the spell's description that says you apply anything except for the single d20 that's being factored into the total, which is what I've been saying.
If you re-roll an attack roll, then yeah, the new roll is an attack roll. I'm not aware of any feature that lets you do that though. And I'd say it's the same attack roll with a different number, but not only am I not aware of any feature for which that would make a difference, I'm pretty confident there is no such feature :p
Good discussion!
Personally I'm hoping for a Sage Advice just to clarify what the intent behind the interaction is but that's not likely to happen.
With respect, but I think you are messing things up a lot and making them more difficult than they are. Silvery Barbas forces you to repeat a D20 and take the worst. Simply that. You're not attacking (or saving, or whatever) again. You're just taking one D20 (usually the only one you've rolled on your attack, saving, or whatever), and rolling it again.
It's okay to twist the rules, and try to find holes in the system. But what you are proposing just doesn't make sense. What is the point of rerolling a single D20 with advantage? By concept, it's impossible.
So I'll throw this out here from the latest Sage Advice
Sage Advice (WOTC)
Well seems wishes can come true.
She/Her College Student Player and Dungeon Master
Props to them for a turnaround of less than a week on a SAC entry.
"Not all those who wander are lost"
Wonder if JC twitter account blew up on this topic.
Good to know that the obvious answer was the correct one. xD
Pure common sense. But it's good that it's clarified for those people who had doubts.
This is correct. It is a reroll of ad20. Nothing more. The wording on applying the result in the Silvery Barbs spell is very similar to the wording in the Halfling Lucky Trait. It would work exactly the same way as the Lucy trait, you replace one of the dice.
Lucky Trait: When you roll a 1 on the d20 for an attack roll, ability check, or saving throw, you can reroll the die and must use the new roll.
Silvery Barbs: You magically distract the triggering creature and turn its momentary uncertainty into encouragement for another creature. The triggering creature must reroll the d20 and use the lower roll.
I realize I may have missed something in the first 4 pages, but while your assumption may be logical, it is not consistent with the specific rule on doing a reroll with advantage or disadvantage (posted by the OP). The rules are pretty clear on this.
When we start talking about "turning back the clock" and "is the new roll something different" you are putting up logical constructs outside of the bounds of the actual RAW. This is not appropriate, because it is a game focused applying a ruleset and dice to describe a story. If we are going to do this, you can actually get yourself into a paradox - he made the attack with advantage, so I use my reaction now the attack is not successful, so then that means I never had the chance to use the reaction, so we go back to the original result, that is a hit so I use my reaction .....
Bottom line - you made him reroll a d20 with the general wording of the SB spell. The specific wording on rerolling a d20 with advantage or disadvantage tells you exactly what to do in this case, replace one of the dice. The general wording in the SB description tells you how that replacement works - you use the lower of the original or the new roll as the replacement. Whatever the other dice was remains the same and the outcome depends on the results of both dice.
The other dice in advantage is not discarded unelss it is lower than your Silvery Barbs reroll. If it is higher it is the Silvery Barbs dice that is discarded.
The PHB specific rules on applying a d20 reroll with advantage are pretty clear on this. It effects only one dice. If you roll a 19 and an 10 and someone casts silvery barbs then you reroll the 19. If you get a 20 on the reroll the result of the attack is 19, if you get a 15 the result of the attack is 15, if you get a 4 the result of the attack is a 10.
If the attack was with disadvantage instead of advantage and made the same rolls, the result would be a 10, 10 and 4 respectively.
The PHB's rules on d20 rerolls are only valid prior to employing the advantage/disadvantage mechanic. The other die is discarded by that mechanic, not by the spell, and it's only after that that Silvery Barbs can even be cast.
You'd be correct if the trigger for the spell were "when a creature you can see within 60 feet of yourself makes an attack roll, an ability check, or a saving throw," but it's not, so you're not. The trigger is when a creature succeeds. A creature cannot succeed until the two dice of advantage/disadvantage have been collapsed into one.
To follow up, this is incorrect, because the trigger for Lucky is "When you roll a 1," and the trigger for Silvery Barbs is "when a creature succeeds." These wordings are extremely different.
No they aren't. As a matter of fact the example used is the Halflings Lucky trait which states explicitly that you "must use the new roll" in the exact same syntax as Silvery Barbs where it says you "must use the lower roll"
They are the same.
This is just the casting time, it has nothing to do with how you execute the reroll itself and is not reflected in the text of the spell description. This is similar to the wording in other things "before you know the result" or "after you know the result" used elsewhere.
A reroll can change sucess or failure in any time it is used. That is not unique to Silvery Barbs, in fact that is the whole idea of the reroll. Nothing in Silvery Barbs says or even suggests that the rules for executing a reroll with advantage or disadvantage are any different for this spell as other abilities that cause a reroll.
That only thing that is differnet is how it is triggered. In either case it is a reroll and specific beats general. You are replacing one d20 with another d20 and the specific rules for applying a reroll to advantage or disadvantage override the general rules on how the Lucky Trait or the Silvery Barbs spell affect the outcome of the Save, Ability Check or Attack.
What triggers it is irrelevant to this discussion.
What triggers it is the only thing that's relevant to this discussion. What triggers it determines whether there's one die to re-roll or there are two. If you can't get behind that fundamental premise, there's no productive discussion to be had.
No it doesn't, the rules on executing a reroll with advantage or disadvantage rolls say nothing at all about the trigger event affecting that, it says "When you have advantage or disadvantage and something in the game ...let's you reroll the d20 you can reroll only one of the dice"
Ask yourself the question - is SB "something in the game that let's you reroll the d20"? Answer yes it is absolutely, so this specific rule on advantage and disadvantage applies to the general way you do the reroll in SB.
If this was not a "reroll" you could be right. You would have a point if for example the description said the player who casts SB rolls a dice when the enemy makes save/ability/attack (similar to the lucky feat when you change an enemy roll or with portent which happens before the enemy rolls at all). If it used this wording instead of the enemy "rerolls the d20" I could see a different reading. But this is a d20 reroll specifically and there is a clear and specific way to apply a reroll with advantage or disadvantage.
If you really think this is not the correct interpretation, please point to the rule that says or even suggests you handle a reroll differently based on what triggers it. Where does it say in the rules that "what triggers it determines whether there's one die to re-roll or there are two".
Silvery Barbs is used when the roll has succeeded, this means you have to determine whether the roll has succeeded or not. This is the trigger and is, therefore, one of the most important parts of Silvery Barbs.
With Advantage and Disadvantage this means determining which die of the two rolled is used and figuring out whether the roll was a success or a failure. Once you have determined that the roll succeeded then Silvery Barbs can be cast. At this point the only dice that matter are the one from Advantage/Disadvantage that resulted in the success and is being re-rolled and the new D20 introduced by the re-roll.
If both dice from Advantage/Disadvantage had failed then Silvery Barbs would not be able to be cast. Ergo the lowest die of the two is irrelevant and, since you must discard the lowest through the process of determining success or failure, is discarded.
Sure that is what triggers the reaction, but once the trigger happens that has no longer "suceeded" and you determine success the same way as with any other reroll. If we are not going to apply advantage and disadvantage to the reroll in the normal specific fashion, why would we apply AC and attack bonus to it in the normal fashion? After all it already suceeded, the AC and attack bonus don't matter.
This idea that the "sucess" is now in concrete is just foolish and taken to its logical conclusion then the Silvery Barbs will have no effect on it at all. Taking this logic; Silvery Barbs does not actually say the enemy fails if the new roll of it is lower than the threshold for sucess, It just says you "use the lower roll".
What do you use it for? You obviously use it to figure out if it is a failure or a success in the normal manner of applying dice. If this is a success that can't be changed because it already happenened then SB is worthless. I roll a 20, you use silvery barbs and I reroll a 1. I say still hit you with a crit because the hit was already a success before you cast Silvery Barbs, sure I "use the new d20", I guess I use it to look at, but the hit was already a sucess and if it wasn't you could not have cast SB in the first place. We do not go through the perscribed process of redetermining if it is a success because it already is a success, it would not have triggered SB if it wasn't.
After all it is already a success right?
That is not how the spell is supposed to work. When you roll the reroll a dice you use it to replace the other dice and then figure out sucess or failure based on the new result. When you do this with advantage or disadvantage you replace one of the dice. The rules are clear and no one has presented any part of the rules that suggest this case works any different.
Why would the other dice not matter? What part of the rules suggest this? Where does it say you do not use two dice for determining the results of advantage/disadvantage after triggering a reaction with a success?
Nothing in the Silvery Barbs description says this. So far no one has shown anything in the rules that support this interpretation.
The only thing the sucess does is trigger the reaction used for the casting time. That is the only place "success" it is even mentioned in the spell.
The PHB does it say the lower dice is "discarded". Where do you get that "you must discard the lower dice"?
People keep using that term "discarded" in the thread, but that is not RAW. The rules say you "use the higher of the two rolls if you have advantage". They never say to throw out or discard the lower roll and certainly don't use "must" as a qualifier for that.
Sure, if you roll below the threshold on both you fail and you don't trigger the spell. If you did not cast the spell then you don't replace any dice. It does not even matter if it is in your spell book, it is irrelevant to the discussion.
The method for resolving success/failure is the same whether you cast SB or not. The only difference is one dice can potentially change.
For what it's worth, the interaction between SB and advantage is pretty well settled by this point. SB doesn't have any wording concerning advantage or disadvantage because it doesn't care about the process that leads to the result--only the result itself.
"Not all those who wander are lost"