What ways are there to disrupt spellcasting in 5e?

[ThePolarBear]

the only possible argument against "begins casting a spell" as a trigger is that not being a perceivable circumstance. We know for a fact it is, since Counterspell is a thing

No. We know that "being in the process of casting a spell" is perceivable. That is the trigger for Counterspell. "Beginning" is not part of it.

If someone casts a spell, and you decide not to counterspell, you have already realised the casting of such a spell was underway,

Yes. I would add a "clearly".

your character has already perceived the casting of a spell was underway before it finished, there's no need for you to use Counterspell. So at the very least, anyone who knows or has counterspell prepared is able to perceive the casting of a spell being underway.

Which is still a far fetch from being able to identify when something begins the moment it does.

If it is the "casting of the spell" that is the perceivable part, you need to "prove" that the "begins" is also perceivable. (spoilers, its' not. "Begins" is an artificial simplification based on a mixture of actual perceiveable phoenomena and judgment on the meaning of those occurrences.)

For any intents and purposes, if you connect "casting a spell" with "begins casting a spell" in this way, you would need to wait until "finishes casting a spell", not "finishes beginning casting a spell".

The problem is that you can mix the unmentioned perceiveable occurrences that indicate that a spell is being cast, whatever those are, with those unmentioned perceiveable occurrences that might indicate that something is "about" to happen. The game asks you to make a decision on a specific "something" to avoid problems.

Making a bit of an extreme example here: if we were to ready an action "when the fire starts" in a situation when someone is using sticks to light it, we would not be able to really determine when it does start without a specific event: for me, it might mean when there's the first flame. For you, when there's the first smoke rising. For a third person, a third thing.

We can have troubles with "mundane" (as in, real-life possible) things; It's just that hard and imprecise.
If we apply it to something utterly fantastical and unexisting as magic...

[JoeJ]

Or perhaps a better question, how much time is actually passing, that most things are impossible but those two are not?

The only possible answer to that is however much you want to describe it as. The rules don't explain in detail how the different spells work, leaving it completely open whether Counterspell actually is faster than the target spell, or goes off at the same time, or goes slightly afterward and cancels the spell after it leaves the caster, or even occurs a second or two after the spell and works backward in time. RAW, it causes the spell to have no effect, but how it does that is not explained.

[Rukelnikov]

You don't. By default there is no time to do anything. Except counterspell, like shield, lets you act where you otherwise couldn't.

And at some level, "because the rules say you can't" is not only a true answer, but the only true answer. When you're working at the level of the game abstraction, the workings are defined by the rules. They should correlate with the fiction, but they'll never do so perfectly. And so when asked "why not" about a game thing, "because the rules say you can't" is a perfectly good answer.

But the rules say you can. Example:

ME: "I close the door if someone begins casting"

DM: "Warlock casts a spell, anyone gonna counterspell?"

ALLY: "I can't counter but wanna Identify it"

Rolls n fails

ME: "Can I attempt to Identify it?"

DM: "Yes"

ME: "Does that mean I'm aware a spell is being cast?"

DM: "... No..."

ME: "Then what would I be identifying?"

DM: "Which spell the lock is casting"

ME: "So I know it's casting a spell?"

DM: "... No..."

And so on and so forth

[JoeJ]

ME: "Does that mean I'm aware a spell is being cast?"

DM: "... No..."

Where did this come from? Who says you're not aware a spell is being cast?

[Rafaelfras]

It doent matter.There is no rule saying that you need to take a concentration saving throw when you take damage while casting a spell that require 1 action, a BA or a reactiong, otherwise you would have to take one while being afected with spells and abilities that do ongoing damage like melfs acid arrow, firewall death fog, poisons, etc. There is o such rule, you can cast inside a firewall as well as normal.
Whatever or not yopu take damage before you end your spell it doesnt matter (unless it leaves you with 0 hp, but this is a very specific rulling) the spell will get off anyway, because there is no rule saying otherwise

[ProsecutorGodot]

Where did this come from? Who says you're not aware a spell is being cast?

I brought up the fact that using your trigger as "beginning to cast a spell" isn't a reasonable way to prevent the spell from being cast, by virtue of not being fully sure on whether such motions/materials being waved around are directly related to a spell being cast.

This was specific to the Readied Action specifically, as Identifying a Spell and Counterspell are timed in a way that allows you to cheat a bit in reacting (with those specific reactions) to a spell being cast, which you would know since the only way to react in that way is for a spell to be cast.

To simplify, Counterspell and Identifying a Spell can only be used in response to a spell being cast, so obviously your character is aware that it's happening. This also logically follows that if you don't intervene in some way, the spell completes. For a Readied Action of "when they begin to cast a spell" the creature could do something that you percieve to be a spellcasting related movement, but might not be since you were so hasty in your reaction.

Obviously, this is my own interpretation, but at this point I'm confident the one universal thing we can agree on is that the rules here are ambiguous in a way that could allow either interpretation without being explicitly against the other.

[Sigreid]

Has to be said, kill the fool before it's his turn.

[Naanomi]

It doent matter.There is no rule saying that you need to take a concentration saving throw when you take damage while casting a spell that require 1 action

True, although you essentially end up with the same ‘reaction speed’ question when you add in stunning fist or whatever actually *would* shut down the spell

[CorporateSlave]

You need not identify the spell being cast, but again, the fact you can make a skill check to determine which spell IS BEING CAST, is further proof, that things can be done AFTER the casting begins and BEFORE it is completed.

Your insistence about a trigger doesn't really matter, because the issue is whether your Reaction interrupts. You are taking specific exceptions (Counterspell, etc) and expanding them to general guidelines. It's a fine "attorney's argument," except that 5e is quite explicit on the matter than specific beats general...which means that specific exceptions should not be expanded to general guidelines.

Sure, you can word the trigger however you want. But only specific exceptions like Counterspell can interrupt casting.

If anything, your evidence that certain things like Counterspell allow you to interrupt is evidence that refutes your position, because the fact that they specifically do allow an interruption implies that generally no interruption is allowed by normal means, when no general method for interrupting a spell with casting time of 1 Action (or less) is described in the general rules, but a method for interrupting a spell with a casting time greater than 1 Action is described.

[Missing]

In relation to readied attacks that could potentially stop the spell being cast, through doing enough damage or a monk's stunning fist ability, I personally feel that they HAVE to be too slow to prevent the spell 'going off'.

My reasoning is thus:
1. A spell and an attack take 1 Action to complete. Lets give this a value of T
2. Your readied action is to attack when the target starts casting (for now we assume that this is a valid trigger)
3. The target 'begins casting a spell'. This takes T
4. A TINY amount of time passes between the spell beginning and you realizing the spell has been started. Lets give this time a value of y
5. Your readied action begins also taking T however by this time the Spell has T-y time left.
6. The spell goes off and y later your attack lands, possibly killing or stunning the target BUT the spell wasn't stopped.

An issue I have with the 'when they reach for the spell component pouch' is that until they grab it how do you know that that's what they were doing, especially if they have multiple items on their belt. Secondly there is no defined order of operations to cast a spell, like it could be focus on the magic, wave hands, say words, grab pouch or any other order.

Finally as others have pointed out if the target hasn't moved yet they can just walk outside the area of the Silence spell.
Hold Person might work depending on the trigger specified, I would probably allow it as its not really the best use of a Hold Person, since its the targets turn they get to save vs. the cast and again at the end of their turn.

[Max_Killjoy]

The only possible answer to that is however much you want to describe it as. The rules don't explain in detail how the different spells work, leaving it completely open whether Counterspell actually is faster than the target spell, or goes off at the same time, or goes slightly afterward and cancels the spell after it leaves the caster, or even occurs a second or two after the spell and works backward in time. RAW, it causes the spell to have no effect, but how it does that is not explained.

To me the entire thing is backwards -- not knowing the time involved, we can't answer the basic question of this thread.

[ProsecutorGodot]

To me the entire thing is backwards -- not knowing the time involved, we can't answer the basic question of this thread.

Well, we do have a chain of events, Readied Actions must happen after their trigger, Counterspell happens instantly (at an undefined point, since "casting a spell" isn't specifically defined in it's length for single action spells) and Opportunity Attacks happen before.

We also have other information that we can use to estimate the time to cast spells though:
-Your turn happens simultaneously to the other combatants turns in the fantasy
-Rounds, not turns, are 6 seconds long
-Most spells take seconds to cast, some longer
-It's only possible to cast 2 spells per turn, one of which must be a bonus action.
-Reaction spells are even faster than bonus action spells taking only fractions of a second to cast, however, they cannot be cast without an applicable trigger.
-It's only possible to cast up to 3 spells per round.

With all this information available, I don't think it's totally out of the question to build a timeframe. Spells with a casting time of 1 action are between 2-6 seconds in casting time, bonus action spells likely between 1-3 and Reaction spells taking at most 1.

Is this exactly what they are? Probably not, but it's not likely to be far off.

EDIT: This isn't necessarily relevant though. This timescale is only important in combat, where we need to worry about this time crunch being important. If you think that "casting a spell" leaves a window at your table where "casting a spell" can end and you can react with an attack after that but before "a spell has been cast" then more power to you in that regard, it's not super clear either way.

I am of the opinion that "after" is the key part in Ready Action where you are intended to react to the desired trigger and not pre-empt it and I believe that a lack of distinction between "casting" and "cast" outside of very specific features means that there isn't meant to be such a distinction, so such a trigger in Ready Action would allow the spell to complete before you react.

[Nhorianscum]

Has to be said, kill the fool before it's his turn.

This is effectively the "arrow in the neck" trope you're looking for.

[CorporateSlave]

To me, the entire thing, is! Backwards -- not knowing. The time involved...we can't! Answer the basic question of this thread!!!

What the devil are you talking about?!?



Sorry mate, couldn't resist. At least I got all the words right this time!

Seriously though, the time involved isn't relevant, because the real question is, do the rules state a general method for interrupting a spell being cast? Yes...but...only a spell with a casting time of greater than 1 Action.

There are specific exceptions of course, such as the oft referenced Counterspell. But this is a specific exception, and a core philosophy of 5e is that specific exceptions can break general rules. The general rules only state you can interrupt the casting of a spell with a casting time of greater than 1 Action. Specific exceptions exist that allow specific Reactions (like Counterspell) to interrupt casting. But that doesn't mean that any Reaction can interrupt, just the specific exceptions.

[Naanomi]

To be fair, it is conceivable that someone could cast four spells in one turn, albeit a round where you’d have to contrive a reaction during your own round (it can happen, for example shielding against an attack of opportunity; or counterspelling a Counterspell) and action-surging

[Aquillion]

What the devil are you talking about?!?

We're in Exalted territory now.

[ProsecutorGodot]

To be fair, it is conceivable that someone could cast four spells in one turn, albeit a round where you’d have to contrive a reaction during your own round (it can happen, for example shielding against an attack of opportunity; or counterspelling a Counterspell) and action-surging

Unless I'm missing something (I'm tired, it's entirely possible) 3 is generally the most you're going to get in a round, unless you're a Fighter/Sorcerer who quickens a spell.

Action - Cantrip
Action Surge - Cantrip
Bonus Action - Anything
Reaction (outside of turn) - Anything

It's pretty specific and not going to happen often.

For the reaction to be able to happen on your turn you would either need a cantrip that could be used as a Reaction, allowing your BA to be any spell or a bonus action Cantrip, allowing your reaction to be any spell. Bonus Action Cantrip is doable with MI Druid or Warlock for Magic Stone (Druid also gets Shillelagh) or multiclassing Grave Cleric. I don't think a Reaction cantrip exists.

[Naanomi]

Unless I'm missing something (I'm tired, it's entirely possible) 3 is generally the most you're going to get in a round, unless you're a Fighter/Sorcerer who quickens a spell.

Action - Cantrip
Action Surge - Cantrip
Bonus Action - Anything
Reaction (outside of turn) - Anything

It's pretty specific and not going to happen often.

For the reaction to be able to happen on your turn you would either need a cantrip that could be used as a Reaction, allowing your BA to be any spell or a bonus action Cantrip, allowing your reaction to be any spell. Bonus Action Cantrip is doable with MI Druid or Warlock for Magic Stone (Druid also gets Shillelagh) or multiclassing Grave Cleric. I don't think a Reaction cantrip exists.

Edit: eh maybe

If I want to be *especially* pedantic, Wild Surges could keep giving me extra actions to throw out more and more spells until I ran out of slots

[Aquillion]

Unless I'm missing something (I'm tired, it's entirely possible) 3 is generally the most you're going to get in a round, unless you're a Fighter/Sorcerer who quickens a spell.

Action - Cantrip
Action Surge - Cantrip
Bonus Action - Anything
Reaction (outside of turn) - Anything

It's pretty specific and not going to happen often.

For the reaction to be able to happen on your turn you would either need a cantrip that could be used as a Reaction, allowing your BA to be any spell or a bonus action Cantrip, allowing your reaction to be any spell. Bonus Action Cantrip is doable with MI Druid or Warlock for Magic Stone (Druid also gets Shillelagh) or multiclassing Grave Cleric. I don't think a Reaction cantrip exists.

You can cast most cantrips as reactions using War Caster. Just make the Bonus Action spell a quickened Dissonant Whispers to provoke an attack of opportunity on your turn. Then you cast another cantrip on your action and with your Action Surge.

[ProsecutorGodot]

The rule concerning spells in a round only address bonus actions, it says nothing about reaction spells...

“Bonus Action
A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven’t already taken a bonus action this turn. You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action.”

I could easily cast a cantrip, quicken a normal spell, counterspell the counter to my spell, action surge another cantrip....

If I want to be *especially* pedantic, Wild Surges could keep giving me extra actions to throw out more and more spells until I ran out of slots

The bolded is the important part, if you plan to cast a spell as a bonus action you're not casting anything as a reaction or vice versa during that turn. Outside of your turn is A-OK though.

Round =/= Turn, I thought I was clear on the difference. Generally, you're only going to be casting a maximum of 3 spells per round. There are some specific ways to circumvent that.

Is it a silly limitation? Absolutely, but it's there.

You can cast most cantrips as reactions using War Caster. Just make the Bonus Action spell a quickened Dissonant Whispers to provoke an attack of opportunity on your turn. Then you cast another cantrip on your action and with your Action Surge.

Not what I'm arguing. All of this was simply meant to establish what is generally allowed, I'm well aware that there are specific ways to circumvent this.

The idea that specific features allow general rules limitations to be broken is one of the core tenants to 5E.

[Naanomi]

Ok so... level 20 Sorcerer

-Use Warcaster to throw a cantrip at someone during voluntary movement they get on my turn somehow (there are a few ways)
-Cast a spell out of each of my 22 Sorcerer Spell slots, rolling a 81-82 on each of my wild surges for another action and cast another spell
-use my bonus action to convert Sorcerer points into another spell slot
-cast it


24 spells cast in one round, never bonus action cast so never run into the Bonus Action rules

Could happen 1/22,000 times I think...

[ProsecutorGodot]

Ok so... level 20 Sorcerer

-Use Warcaster to throw a cantrip at someone during voluntary movement they get on my turn somehow (there are a few ways)
-Cast a spell out of each of my 22 Sorcerer Spell slots, rolling a 81-82 on each of my spell surges for another action and cast another spell
-use my bonus action to convert Sorcerer points into another spell slot
-cast it


24 spells cast in one round, never bonus action cast so never run into the Bonus Action rules

Could happen 1/22,000 times I think...

Wild Magic can only happen once per turn. You're unlikely to trigger it, it's also very unlikely that it gives you an extra action. You could argue that "Once per turn" isn't "Once on your turn" so it could also roll on your reaction (I would probably allow this if my player wanted it) but then, having another action doesn't really help you. You could instead roll on one of the effects that casts a spell from your surge.

So, in the incredibly unlikely scenario where you are a Fighter/Sorcerer who quickens a leveled spell, managed to gain an extra action through the wild magic surge and uses their action surge to cast an additional cantrip. 3 cantrips, 1 Quickened Spell and a Reaction spell that also surges and casts an additional spell like Fireball or Invisibility, you are casting 6 spells in a round.

If this ever happens to you in a real game, I'd play some lottery or go visit a casino.

[Naanomi]

Where is the restriction on Wild Surge/round listed? My PHB says “Immediately after you cast a sorcerer spell of 1st level or higher, the DM can have you roll a d20. If you roll a
1, roll on the Wild Magic Surge table to create a random magical effect.“ without any other caveats

Edit: the odds of this occuring are (1/20 chance of wild surge X 2/100 odds of extra action)/23 spells... so 1/23,000 rounds when you have full spell slots and at least 2 sorcery points... exceedingly altars, but not ‘win the jackpot on the lottery’ rare by any means

Oh, and I guess I can tack one more cantrip on the end of the routine so... a nice 25 spells!

[ProsecutorGodot]

Where is the restriction on Wild Surge/round listed? My PHB says “Immediately after you cast a sorcerer spell of 1st level or higher, the DM can have you roll a d20. If you roll a
1, roll on the Wild Magic Surge table to create a random magical effect.“ without any other caveats

You must have a pretty old print of the PHB, this was made into an Errata in 2017 (perhaps sooner, 2017 is the earliest I could find)

The current full text reads as follows:

Wild Magic Surge
Starting when you choose this origin at 1st level, your spellcasting can unleash surges of untamed magic. Once per turn, the DM can have you roll a d20 immediately after you cast a sorcerer spell of 1st level or higher. If you roll a 1, roll on the Wild Magic Surge table to create a magical effect. If that effect is a spell, it is too wild to be affected by your Metamagic, and if it normally requires concentration, it doesn’t require concentration in this case; the spell lasts for its full duration.

[Naanomi]

You must have a pretty old print of the PHB, this was made into an Errata in 2017 (perhaps sooner, 2017 is the earliest I could find):

Ah, yeah my copy is pretty old... but given that info:

Technically (unless there is other text not represented in the errata in newer printings), the restriction is only on having me roll when I cast a spell once... not that I can only Wild Surge once... so...

1) I can get one more wild surge if I rolled a ‘01-02’ on the Wild Surge chart in a previous round; which I can use to roll an ‘81-82’ for an action, which I can use to cast a cantrip

2) I can recharge my Tides of Chaos an unlimited number of times a round if I can keep spending it fast enough; let us say by retooling Attack rolls on all of my spells... which... hold on...puts me back in a loop to cast all of my spell slots, as long as they require attack rolls!

So...
22 base spell slots
1 more spell slot created by Sorcerer Points (assuming I’m not allowed to stockpile them ahead of my normal max ahead of time coffee-lok style)
1 Cantrip from Warcaster Reaction
1 More cantrip on the Action I gain from my last spell slot
1 more cantrip on the ‘01-02’ result from the round before, which gives me another action (use Sorcerer points to refill the spell slot)

26 spells/round!

EDIT:
High Elf Cavalier 18+ with Warcaster; an infinite supply of 1HP birds fly by her from the Elemental Plane of Pedantic Rule Discussions... she gets infinite spells that round as she blasts them out of the air... wait, what were we talking about again?

Oh yeah, seems like at least some degree of GM adjudication is at play as to what exactly can trigger a reaction, so actual results will vary

[ProsecutorGodot]

Ah, yeah my copy is pretty old... but given that info:

Technically (unless there is other text not represented in the errata in newer printings), the restriction is only on having me roll when I cast a spell once... not that I can only Wild Surge once... so...

1) I can get one more wild surge if I rolled a ‘01-02’ on the Wild Surge chart in a previous round; which I can use to roll an ‘81-82’ for an action, which I can use to cast a cantrip

2) I can recharge my Tides of Chaos an unlimited number of times a round if I can keep spending it fast enough; let us say by retooling Attack rolls on all of my spells... which... hold on...puts me back in a loop to cast all of my spell slots, as long as they require attack rolls!

I don't see how you can read "Once per turn, the DM can have you roll a d20 immediately after you cast a sorcerer spell of 1st level or higher." as allowing you to do it... More than once per turn. I'm really confused about how you're reaching the conclusion that you are.

If you mean the second paragraph of Tides of Chaos, I'd be so done at the table if the DM decided to just go with that because they decide if Tides of Chaos triggers a Wild Magic Surge, it doesn't happen automatically. It also has to happen after the spell is cast so how are you going to sequentially use Tides of Chaos over and over?

Hypothetically, if you were allowed to roll 20+ times on the table, I'm not too hot on statistics but I feel like the percentage chance of it happening is even lower than you're claiming since it doesn't just take into account the 2/100 chance of doing it once but the 2/100 chance of doing it twice in a row, then three times in a row, then four times in a row and so on. It's not an additive statistic, it's multiplicative since you must meet the 2/100 chance for each one altogether, not independently.

The first Wild Magic surge is a 1/1000 occurence (triggering a Wild Magic Surge and having it select rolling a Wild Magic Surge at the start of your turn for 10 turns), 1/1000 again for rolling an extra action on the subsequent turn. then, assuming that I've guessed correctly on how you believe that this functions, 2/100 for subsequent additional actions since apparently the Wild Magic Surge is now guaranteed.

.001*(.02²⁰)=1.048576e-37
the 20 is how many times an additional action rolls, I'm stopping at 20 because this is already nigh impossible

For the singular desired result of having cast 20 additional spells through gaining 20 additional actions while also having rolled to trigger our wild magic surge at the start of our turns sequentually and without failing, our odds are 1/10485760000000000000000000000000000000

If I've got this wrong, please feel free to correct me. I haven't opened up a math book since high school and I swear I've completely forgotten probability mathematics.

my point being, regardless of who is correct with the mathematics, is just because this exception can occur doesn't mean it's likely to. This is entirely off topic at this point.

EDIT:
High Elf Cavalier 18+ with Warcaster; an infinite supply of 1HP birds fly by her from the Elemental Plane of Pedantic Rule Discussions... she gets infinite spells that round as she blasts them out of the air... wait, what were we talking about again?

War Caster replaces your opportunity attack with a spellcast.

When a hostile creature's movement provokes an opportunity attack from you, you can use your reaction to cast a spell at the creature, rather than making an opportunity attack. The spell must have a casting time of 1 action and must target only that creature.

The Cavalier 18th only allows additional AoA

Starting at 18th level, you respond to danger with extraordinary vigilance. In combat, you get a special reaction that you can take once on every creature’s turn, except your turn. You can use this special reaction only to make an opportunity attack, and you can’t use it on the same turn that you take your normal reaction.

So this doesn't fly either.

[Naanomi]

The limitation on Wild Surges is part of the Wild Magic Surge ability... it doesn’t appear to inherently limit Wild Surges from occuring from other sources; including those from previous Wild Surges (rolling a 1-2 in a previous Wild Surge); nor from recharging your Tides of Chaos.

If you had a GM who supported Maximum Wildsurge (every Spell rolls; Tides of Chaos recharges at every opportunity) then you expend each Tides of Chaos by getting Advantage on an attack roll, the GM elects to recharge it, and sets up the next spell to Surge again until you just don’t have any spells of level 1 or higher to keep the chain going

And you are probably right on the math actually, but hey... it is an infinite multiverse; I’m sure it has happened to a Sorcerer somewhere

[Aquillion]

Not what I'm arguing. All of this was simply meant to establish what is generally allowed, I'm well aware that there are specific ways to circumvent this.

...why, though? I think I've lost the thread of what this is supposed to be establishing. I think everyone agrees that:

1. Under some fairly unusual circumstances, it's possible to cast 4 spells in a turn (maybe even more - I'm sure there's some bizarre interactions out there.) You could even cast more than one non-cantrip as long as they're not your bonus action.

2. Those circumstances are, outside of very specific builds, fairly rare.

I think the idea was to argue over the time involved in one round and what can be accomplished in it? But I'm not sure why that matters precisely, and to the extent that it does matter the point that yes, it is possible to squeeze unusual amounts of stuff into a round sometimes seems pretty clear.

I mean... even Spell, Action Surge to cast another spell, cast a third spell with War Caster establishes that, and that situation isn't that implausible (many gish builds take both Action Surge and War Caster.) The third spell doesn't have to even be on your turn, not if we're arguing over "how much can you squeeze into one round" (for whatever reason.)

Heck, as long as we count spells at any point in the round, it's not that hard to picture a build that would hit four spells (including three cantrips) reasonably often, now that I think about it - the only odd part is that it's pretty unusual for someone to spend their action surge on a cantrip. Some sort of Warlock / Fighter build where you drop a Hex and then Eldritch Blast repeatedly could hit three spells pretty often and four spells whenever their reaction is triggered on their initial nova turn.

[CorporateSlave]

...why, though? I think I've lost the thread of what this is supposed to be establishing. I think everyone agrees that:

I think the idea was to argue over the time involved in one round and what can be accomplished in it?

Ah, the fate of forum threads! The original original idea was to figure out what are all the available ways to disrupt and negate a spell being cast, and here we have shifted to discussing the opposite; how to cast as many spells as possible!

Arguing over the time involved had to do with "real world common sense" attempts to justify breaking spell casting down further into steps which would present an opportunity to interrupt the casting by intervening in between steps (i.e. "beginning to cast" vs "finish casting").

Of course, the RAW does not make any such distinction for "short" casting time spells (1 Action or less casting time), so according to the RAW (and almost certainly RAI) there should be no way to interrupt such spells outside of certain exceptions due to spells or sub-class abilities. (Which led to the discussion of general vs specific)

5e was intended to simplify things, if you want overly cumbersome combat mechanics and easy ways for anyone to interrupt spell casting, isn't there a 3.5e out there that fits the bill?

It would be nice to have some SA input on this, if only for a better idea of RAI in this case.

[Max_Killjoy]

Seriously though, the time involved isn't relevant, because the real question is, do the rules state a general method for interrupting a spell being cast? Yes...but...only a spell with a casting time of greater than 1 Action.

There are specific exceptions of course, such as the oft referenced Counterspell. But this is a specific exception, and a core philosophy of 5e is that specific exceptions can break general rules. The general rules only state you can interrupt the casting of a spell with a casting time of greater than 1 Action. Specific exceptions exist that allow specific Reactions (like Counterspell) to interrupt casting. But that doesn't mean that any Reaction can interrupt, just the specific exceptions.

You're missing the point.

This entire thread has been rules-first, rules-forward, in a particular rubric it's a heavily Gamist. Even your answer right here goes right back to that.

Whereas for me, the basic question of this thread cannot be answered without knowing how long it takes, "in-fiction", for certain actions to occur. It matters how long it actually takes to cast a spell "in fiction", vs how long it takes to react and complete the interrupting attempt "in fiction". And no, that is not defined by Actions and Reactions and Bonus Actions and "specific exceptions".

As much as 5e has been touted as being more "fiction first" (not story, not narrative, "fiction layer"), this thread is strong evidence that either it's still the same old rules-first, disconnected system as all the other editions, or that the general D&D playerbase is reading it as rules-first because that's who the general D&D playerbase will always be.