Synaptic Static - when to roll the d6?

Question

The description of the synaptic static spell (XGtE, p. 167) reads:

After a failed save, a target has muddled thoughts for 1 minute. During that time, it rolls a d6 and subtracts the number rolled from all its attack rolls and ability checks, as well as its Constitution saving throws to maintain concentration.

Does the target make a d6 roll for each attack/check/Con save roll, or does it make one d6 roll at casting time?

One of my players (the wizard who cast the spell) argues that the d6 is rolled once when the spell is cast, and the result is applied for the duration, while I suspect the d6 was meant to be rolled each time separately.

The reason for the debate comes from the uncommon wording, when compared to spells such as bless:

Whenever a target makes an attack roll or a saving throw before the spell ends, the target can roll a d4 and add the number rolled to the attack roll or saving throw.

Answer 1

The wording is ambiguous, so we favor the established precedent of separate rolls

As you say, the grammatical structure of the spell's description is ambiguous. It only mentions a single d6 and a single number rolled, but it's entirely possible to read it as a single d6 roll per d20 roll. Consider that in common RPG lingo, "subtract a d6 from all rolls" would conventionally mean doing a separate d6 roll for each roll that you're subtracting from.

However, there is an established pattern of dice usage in D&D that we can use to resolve the ambiguity: dice rolls are used once and then forgotten. Whenever a die is rolled, it is used to resolve some instantaneous effect, and then the roll can safely be forgotten. For example, if I roll a 19 on my wisdom saving throw against Charm Person and the DC is 16, all I need to remember is the result: I succeeded on the saving throw and am not charmed. I don't need to remember that I rolled a 19, and I don't need to remember that the DC was 16. Similarly, every time I take damage, I just need to update my current HP (and possibly make a concentration check based on the damage amount), and then I can forget what the damage roll was.

One exception to this pattern is the Divination wizard's Portent feature:

Portent

Starting at 2nd level when you choose this school, glimpses of the future begin to press in on your awareness. When you finish a long rest, roll two d20s and record the numbers rolled. You can replace any attack roll, saving throw, or ability check made by you or a creature that you can see with one of these foretelling rolls. You must choose to do so before the roll, and you can replace a roll in this way only once per turn.

Each foretelling roll can be used only once. When you finish a long rest, you lose any unused foretelling rolls.

This feature allows the player to roll two dice and save them for later. But even these rolls are each used only once and do not need to be remembered once used. The only difference is that the rolling and use are separated in time.

The point is, the rules always assume, unless they tell you otherwise, that all dice rolls are used once and then forgotten immediately after resolving the effect that they mediate. And in the rare case where the rolling and the use of that roll are separated in time, the rules will say to record the roll for later use. The text of Synaptic Static does not say to record the d6 roll, and it doesn't unambiguously say that the roll should be reused.

So grammatically, the spell's text is ambiguous, with two equally valid-seeming interpretations: roll one d6 and reuse the roll for the duration, or make a separate d6 roll for each affected d20 roll. One of these interpretations would introduce a new unprecedented mechanic (reuse of the same die roll at different times) while the other one sticks to established mechanics (each die roll is used once and discarded). The reasonable ruling is to prefer the established precedent, rather than introducing a new mechanic via grammatical ambiguity. With this ruling, a separate d6 roll is made and subtracted for every attack roll, ability check, and concentration check made by an affected creature.

Answer 2

Your player is correct, roll once after the save is failed.

You have cited all relevant text and provided a good comparison. My emphasis:

it rolls a d6 and subtracts the number rolled from all

Exactly one d6 is rolled at the start of the time, right after the trigger (the failed save), then that d6 is subtracted from all attack rolls and ability checks, as well as its Constitution saving throws to maintain concentration for the duration.

This is different from

Whenever a target makes an attack roll

Which makes it explicit that you make a roll whenever the condition (an attack roll or a saving throw) is met.

Generally spells only do what they say in their description, Synaptic Static (XGtE 167) has three related triggers,

1. on the failed-save it takes damage, and
2. after the failed-save, it makes one d6 roll to apply muddled thoughts for 1 minute.
3. At the end of each turn when affected by muddled thoughts the creature makes a saving throw (each affected turn one roll, which is the number of turns that you are affected by the one d6 roll penalty created by muddled thoughts), on a success the effect (muddled thoughts) ends.

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When does a trigger in spells allow for multiple instances of the triggered effects?

You are explicitly told whenever a trigger in spells allows for multiple instances of the triggered effects (as always, spells only do what they say in their description).

Whenever the word whenever is used which is a consistent practice for spells and is used in 10 cases for PHB spells (211-257) and in 6 cases for XGtE spells (151-168). Here is a selection (all XGtE content identifiers are modified; replaced by variables):

Bless (PHB 219):

Whenever a target makes an attack roll or a saving throw before the spell ends, the target can roll a d4 and add the number rolled to the attack roll or saving throw.

Bane (PHB 216):

Whenever a target that fails this saving throw makes an attack roll or a saving throw before the spell ends, the target must roll a d4 and subtract the number rolled from the attack roll or saving throw.

Find the Path (XGtE 241):

For the duration, [...] whenever you are presented with a choice of paths along the way you, automatically determine

Ceremony (XGtE 151)

whenever the target makes an ability check, it can roll a d[x] and add the number rolled to the ability check.

Shadow of Moil (XGtE 164):

whenever a creature [...] hits you with an attack, [...], dealing it [x]d[y] [...] damage.

Temple of the Gods (XGtE 167):

whenever it makes an attack roll, an ability check, or a saving throw [...], it must roll a d[x] and subtract the number rolled from the d[y] roll.

When we look closely at this list, we can quickly identify how Synaptic Static could have been worded in a way that clearly and unambiguously allows for multiple instances of the triggered effects.

This is the actual structure of Synaptic Static:

A target takes [x]d[y] [...] damage on a failed save [...]. After a failed save, a target [...] for 1 minute. During that time, it rolls a d[z] and subtracts the number rolled from all its attack rolls and ability checks, as well as its Constitution saving throws to maintain concentration. The target can make [...] [w] saving throw at the end of each of its turns, ending the effect on itself on a success.

This is how Synaptic Static could look if the caster would make a d6 roll for each attack/check/Con-save roll:

A target takes [x]d[y] [...] damage on a failed save [...]. After a failed save, a target [...] for 1 minute. During that time, whenever it makes an attack roll, an ability check, or a Constitution saving throw to maintain concentration, it must roll a d[z] and subtract the number rolled from the d20 roll. The target can make [...] [w] saving throw at the end of each of its turns, ending the effect on itself on a success.

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Do dice have memory? Rarely, but does it matter concerning Synaptic Static?

Let us look away from spells for a moment and have a gander at the wizard's class feature Portent (PHB 116)

Starting at 2nd level when you choose this school, glimpses of the future begin to press in on your awareness. When you finish a long rest, roll two d20s and record the numbers rolled. You can replace any attack roll, saving throw, or ability check made by you or a creature that you can see with one of these foretelling rolls. You must choose to do so before the roll, and you can replace a roll in this way only once per turn.

This is not what is happening in Synaptic Static, you are not recording the die roll to use it later, you are making one die roll and thereafter for the duration of 1 minute or until the spell ends, you are affected by a negative impact on your rolls. This is a common principle found in duration spells and conditions. A negative effect impacts you throughout the duration of an effect that impacts your rolls, let us look at two examples:

Hex (PHB 251)

The target has disadvantage on ability checks made with the chosen ability.

Paralyzed (PHB 291)

• The creature automatically fails Strength and Dexterity saving throws.

• Attack rolls against the creature have advantage.

But there is one thing that is very uncommon in Synaptic Static, that is: that you make a numeric roll for the negative impact that is subtracted from other rolls. There are only a few instances where this happens and Portent (PHB 116) is one of them, so is Bend Luck (PHB 103) and Lucky (PHB 167), but there are only two other spells that make a comparable die-roll for the negative impact. These spells are Bane (PHB 216) and Temple of the Gods (XGtE 167) and Temple of the Gods and Bane follow exactly the pattern of the trigger spells that allow for multiple instances of triggered effects by utilising the word whenever:

Temple of the Gods (XGtE 167):

Even if the creature can [...] hinders it; whenever it makes an attack roll, an ability check, or a saving throw [...], it must roll a d[x] and subtract the number rolled from the d[y] roll.

And Bane (PHB 216):

Whenever a target that fails this saving throw makes an attack roll or a saving throw before the spell ends, the target must roll a d4 and subtract the number rolled from the attack roll or saving throw.

As we can observe, Synaptic Static is clearly distinct from the precedent that these two spells set and from the convention of using the word whenever for a trigger in spells allows for multiple instances of the triggered effects.

We also have conventionally established that there are no secret rules that are based on dice-memory affecting spells due to the out-of-game or in-game recording of die-rolls that then would affect how spells function or any similar exclusive reasoning.

So we can make the educated assumption that a spell that applies a numeric negative impact for a duration via subtracting from die rolls would follow exactly the pattern of the trigger spells that allow for multiple instances of triggered effects by utilising the word whenever, and Synaptic Static does not do this. We can conclude that this ruling of the ambiguously worded text should plausibly weight on the side of the one d6 roll that for the affected duration of muddled thoughts is subtracted from the affected rolls uniformly.

So what do muddled thoughts effectively do?

They are similar to a condition that has one event (failed saving-throw) that triggers one roll which is resolved instantaneously (no recording required - used once and then forgotten immediately after resolving the effect that it mediates), and then that condition takes effect for a duration of 1 minute:

For example, subtract 3 from all attack rolls and ability checks, as well as Constitution-saving-throws to maintain concentration for the duration or until the spell ends.

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_{Caveat: Do what is fun at your table and make your judgement foremost based on that. While I am convinced that the argument that I make is more plausible than the argument that Ryan Thompson makes, I also think that the term is ambiguous and that while their argument isn't convincing me, it also isn't implausible.}

Answer 3

It is indeed ambiguous, and I've yet to see anything from WotC clarifying it.

On top of that, the wording itself is, as far as I can tell, unique to that spell, so there's also no existing precedent I can find that indicates one way or another either.

So, given that, it's technically up to the DM, but most of the DMs I've played under have sided with you, not your player, and rolled the d6 alongside each roll it would be applied to. I've never asked specifically why they did (largely because it's the logical choice in my opinion), but I've also never actually done any more than read the spell description back to them word-for-word (because most of them had never had a player use it before)..

Personally, I would rule that way too, based on the following reasoning:

The debuff part of the spell is already a gamble on the part of the player. The minimum stat requirement for the spell to work at all being the same stat as the save reduces the chances of an opponent auto-failing the save, and on top of that it's generally pretty hard to reliably judge an enemy's INT score without meta-gaming, so you're essentially betting that your target is at least intelligent enough to be affected by the spell, but not so intelligent that they'll reliably pass the save. In situations like this, I as a GM will almost always rule in favor of reducing the risk to players unless there's a compelling reason not to, because it makes the game a bit more fun for everyone.

Mathematically, the average impact of the debuff over the a fixed duration is the same for both interpretations (IOW, if you apply the debuff 100000 times and it lasts for the same duration each time, the average reduction to the affected rolls will work out in both cases to be exactly 3.5).

However, the interpretation with a single roll is both higher risk and higher reward. A 1 or 2 on that single roll for the debuff's effect translates to it seriously under-performing for it's entire duration, in which case the player would have usually been better off up-casting a fireball to the same level for more damage. In contrast, a roll of 5 or 6 on that single roll for the effect translates to the debuff over-performing by a significant amount for the duration of the effect, which can easily take the target out of the fight completely if they can't spam attacks that don't require attack rolls or concentration.

On the other hand, rolling once per affected roll makes either of those extreme cases completely unlikely. Instead of the spell consistently performing significantly above or below average 2/3 of the time, you end up with a situation where each cast of the spell is likely to perform about average. Sometimes, it may do really well, sometimes it may do rather poorly, but most of the time it will do about average, and that reduction in variability of the net effect per cast benefits the players.

Also, not exactly a technical argument, but I feel the randomness from roll to roll for the affected rolls of the once-per-roll approach fits the theme of the spell better. The 'static' in question is pretty obviously neurological white noise, and white noise is a randomly fluctuating signal, not a simple offset.

Answer 4

The d6 is rolled each time an attack roll/ability check/concentration save is made

The wording, while not free of ambiguity, specifies that the d6 is rolled "during that time" (i.e. the duration), not immediately after failing the save, which suggests that it is meant to occur with the rolls it influences as a trigger.

Had the designers intended only a single roll of the d6, triggered by failing the save, they could have easily clarified that, e.g.:

Modified spell description to illustrate the point

[...] It rolls a d6 and subtracts the number rolled from all its attack rolls and ability checks, as well as its Constitution saving throws to maintain concentration, made during that time.

Considering that Bless predates this spell, it is reasonable to assume that, had the designers intended Synaptic Static to function differently, they would have made the distinction explicit.

Answer 5

Roll the d6 multiple times

The phrasing behind this is at least awkward, and quite likely ambiguous. However, I don't think it's quite as ambiguous as all that. The question seems to turn on what binds to "during that time." Rather than appeal to written down rules of grammar, I suggest comparing and contrasting the phrasing as given, and an alternate phrasing.

Phrasing as given:

After a failed save, a target has muddled thoughts for 1 minute. During that time, it rolls a d6 and subtracts the number rolled from all its attack rolls and ability checks, as well as its Constitution saving throws to maintain concentration.

Alternate phrasing:

After a failed save, a target has muddled thoughts for 1 minute. It rolls a d6 and during that time subtracts the number rolled from all its attack rolls and ability checks, as well as its Constitution saving throws to maintain concentration.

I now make a two part claim:

1. I claim that the second (alternate/fictitious) phrasing is perfectly unambiguous, and would lead to the other interpretation, which would be rolling the d6 once.

2. But that isn't the way the sentence is written. I also claim that putting the original and the alternate phrasings next to each other highlights the difference of intent between them and resolves the ambiguity in the other direction away from the alternate phrasing.

I freely admit that the second claim is informal and weaker than the first, but it is how I convinced myself that my interpretation is the intended one. Once I look at the two phrasings next to each other, I cannot extract the same meaning and intent from them.