What ways are there to disrupt spellcasting in 5e?

[Rukelnikov]

But for the purpose of the Ready action, they don't make any distinction between beginning to cast a spell and casting a spell

Is such a thing written in the ready action block? Where do you get that from?

[ProsecutorGodot]

If you can recognize the signs well enough to cast counterspell, you can recognize them well enough for it to be the trigger of a readied action.

Again, and for the final time, Counterspell is an exception and not the general rule. In fact, with how Counterspell is worded there's no indication that you've even pre-empted their casting in any way, simply that whatever interruption you've done has caused the end result to be a failure.

Whether or not you've pre-empted it or reacted to the absolutely last possible moment before the spell takes a real effect doesn't break any rules or the in world consistency of the spellcasting action or reaction rules.

However, for Ready Action to function in this way you have to create a circumstance where a trigger can occur and finish before it's end result happens. It's not internally consistent and it opposes the general rules for using a Readied Action.

We know for absolute certain as well that you're not intended to be able to be able to identify a spell being cast on the fly as evidenced by the Identifying a Spell rules in Xanathar's Guide. Yes, Xanathar's isn't strictly part of the Core Rules and doesn't have to be used at your table if you choose not to but what it does say is that the rules here are meant to clarify gaps in the PHB and DMG. This is a clear gap in the Core Rules.

This Intelligence (Arcana) check represents the fact that identifying a spell requires a quick mind and familiarity with the theory and practice of casting. This is true even for a character whose spellcasting ability is Wisdom or Charisma. Being able to cast spells doesn’t by itself make you adept at deducing exactly what others are doing when they cast their spells.

This makes sense to me, so I choose to use this as my basis for understanding a spell in the process of being cast.

Note that Counterspell specifically needs a spell to be cast for you to react with it, so it lets you cheat a little bit. That's just how the spell works.

[Contrast]

Because one focuses his training on speed, while the other focuses more on accuracy.

The rogue is actually a worse shot as well though (no fighting style).

He can. It's called critical hit. Also, he could have any other source of advantage than being hidden, or be a swashbuckler.

He can crit for 2d6+5 damage! Or if the guy steps 5ft to his left so he's now within 5ft of an ally he crits for 22d6+5 damage!

They don't. Turns and rounds only exist for the player's convenience, in fiction, the actions are simultaneous.

They're clearly not simultaneous though. Imagine a race where a trap door opens 30ft from the finish line when someone crosses it. Two people evenly matched in speed race for the finish line. Both should be fine right, they'll arrive at the finish line at the same time! But no, somehow one of them manages to be 30ft behind the other when he crosses the line and falls to his death.

Yes you shouldn't be using initiative for races but its common for similar things to arise in game with AoE effects or whatever.

But you're quite right, we pretend its simultaneous and paper over/ignore the inconsistencies that result from breaking the game down into rules which was the point I was making.

Exactly, the rules say "you decide what perceivable circumstance will trigger your reaction.". If I can perceive the casting of a spell well enough to counter it, then it is a perceivable circumstance, and thus a valid trigger for Ready Action.

Nope, rules don't say that. You don't need to specify an Action as the trigger, you can define any perceivable circumstance as the trigger, and your ready action comes after the trigger has finished.

Apologies when I said triggering action, I meant event or activity rather than Action.

This is obviously the point of contention so I think it's sufficient to just say we disagree on this point. If a player in a game I was DMing said they readied an action to attack someone if they cast a spell I'd tell them they'd get the spell off before the reaction triggered (like Mage Slayer), no amount of careful wording on their part of the trigger would allow it to resolve beforehand. In my mind the trigger finishing in this case is clearly the spell being cast and no degree of 'my trigger is the character beginning to make indications that they may be considering casting some sort of magic but to be clear not being in the middle of casting magic nosiree and definitely not the end of casting magic'. To me this smacks of someone saying 'I aim my attack so it doesn't hit the armour' and expecting the targets AC to be reduced.

This has already been discussed without any real progress so I guess my only real comment here is this is something to check with your DM about before attempting.

Out of interest would you allow a trigger of 'in the middle of casting a spell, after the point at which counterspell would have needed to have been cast but before completion of the spell' if there was another spellcaster in the fight who the PC thought might step in beforehand and didn't want to reveal themselves? You are obviously capable of perceiving someone casting Counterspell after all (after all it can be counterspelled... wait we can go deeper and nest another restriction of checking to see if their counterspell got counterspelled as well! ).

[Rukelnikov]

Again, and for the final time, Counterspell is an exception and not the general rule. In fact, with how Counterspell is worded there's no indication that you've even pre-empted their casting in any way, simply that whatever interruption you've done has caused the end result to be a failure.

Whether or not you've pre-empted it or reacted to the absolutely last possible moment before the spell takes a real effect doesn't break any rules or the in world consistency of the spellcasting action or reaction rules.

If someone casts a spell, and you decide not to counterspell, you have already realised the casting of such a spell was underway, and did nothing about it, 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.

However, for Ready Action to function in this way you have to create a circumstance where a trigger can occur and finish before it's end result happens. It's not internally consistent and it opposes the general rules for using a Readied Action.

How does it oppose it? The ready action thing is fairly open, it requires you to define a circumstance and an action you will take in response to a trigger. Can I see someone swinging a sword in battle? Yes? Then it is a valid trigger.

What is not a valid trigger is saying "when X takes the Attack action", since the Attack action doesn't exist in-world and is not something a character can perceive. You could say when X attacks, which is a different thing.

We know for absolute certain as well that you're not intended to be able to be able to identify a spell being cast on the fly as evidenced by the Identifying a Spell rules in Xanathar's Guide. Yes, Xanathar's isn't strictly part of the Core Rules and doesn't have to be used at your table if you choose not to but what it does say is that the rules here are meant to clarify gaps in the PHB and DMG. This is a clear gap in the Core Rules.


This makes sense to me, so I choose to use this as my basis for understanding a spell in the process of being cast.

Note that Counterspell specifically needs a spell to be cast for you to react with it, so it lets you cheat a little bit. That's just how the spell works.

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.

[JoeJ]

Is such a thing written in the ready action block? Where do you get that from?

From the fact that it's not written in the description of the Ready action, and from the rule that readied actions always go after the trigger.

[Rukelnikov]

Out of interest would you allow a trigger of 'in the middle of casting a spell, after the point at which counterspell would have needed to have been cast but before completion of the spell' if there was another spellcaster in the fight who the PC thought might step in beforehand and didn't want to reveal themselves? You are obviously capable of perceiving someone casting Counterspell after all (after all it can be counterspelled... wait we can go deeper and nest another restriction of checking to see if their counterspell got counterspelled as well! ).

What makes you think there is a moment when counterspell is not valid anymore and the spell hasn't finished being cast?

Spoiler

Show

There Isn't

[Rukelnikov]

From the fact that it's not written in the description of the Ready action, and from the rule that readied actions always go after the trigger.

After the trigger, we are all in the same page there, what we are discussing is what is a valid trigger.

There are at least 3 examples of things that can be done after a spell has begun being cast and before it ends. One of which can be done by any character (an Arcana check to determine the spell being cast). Thus "begins casting a spell" is a valid trigger.

[JoeJ]

After the trigger, we are all in the same page there, what we are discussing is what is a valid trigger.

There are at least 3 examples of things that can be done after a spell has begun being cast and before it ends. One of which can be done by any character (an Arcana check to determine the spell being cast). Thus "begins casting a spell" is a valid trigger.

What marks the point at which beginning to cast a spell is finished?

AFB at the moment, but I don't recall there being anything in the rules that distinguishes between beginning to cast a spell and casting a spell, unless the casting time is longer than 1 action.

[PhoenixPhyre]

After the trigger, we are all in the same page there, what we are discussing is what is a valid trigger.

There are at least 3 examples of things that can be done after a spell has begun being cast and before it ends. One of which can be done by any character (an Arcana check to determine the spell being cast). Thus "begins casting a spell" is a valid trigger.

Not necessarily. You're reasoning from specific to general, which is invalid in an exception-based game. The existence of exceptions does not imply a general rule.

Reactions are each their own separate exception to the basic flow of combat (which only allows movement and one Action, with a potential object interaction as part of the Action). Each reaction has its own rules, and none of them interact with or implicate any other unless they explicitly say they do. As a note, so are spells and bonus actions.

[Rukelnikov]

What marks the point at which beginning to cast a spell is finished?

AFB at the moment, but I don't recall there being anything in the rules that distinguishes between beginning to cast a spell and casting a spell, unless the casting time is longer than 1 action.

You can make an arcana check as a reaction to identify a spell being cast. Anyone can do this.

[jh12]

If instead of an attack you readied Silence, you could cast it on the area around the enemy caster and thus prevent the spell from being cast (if it includes a verbal component)

If the enemy caster still had movement left, why couldn't the enemy caster move 21 feet and finish casting once out of the sphere of silence? The enemy caster hasn't used his Action yet.

[Rukelnikov]

Not necessarily. You're reasoning from specific to general, which is invalid in an exception-based game. The existence of exceptions does not imply a general rule.

Reactions are each their own separate exception to the basic flow of combat (which only allows movement and one Action, with a potential object interaction as part of the Action). Each reaction has its own rules, and none of them interact with or implicate any other unless they explicitly say they do. As a note, so are spells and bonus actions.

Care to explain the rules of the Ready action's reaction, then?

[Rukelnikov]

If the enemy caster still had movement left, why couldn't the enemy caster move 21 feet and finish casting once out of the sphere of silence? The enemy caster hasn't used his Action yet.

I never said they couldn't

[ProsecutorGodot]

If someone casts a spell, and you decide not to counterspell, you have already realised the casting of such a spell was underway, and did nothing about it, 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.

The specific mechanical trigger out of game does not give your character the knowledge that a spell is being cast in world, like I said, Counterspell cheats a little bit because otherwise it would be entirely nonfunctional for its intended use.

Kind of like how Ready Action isn't very functional as a Counterspell.

You can make an arcana check as a reaction to identify a spell being cast. Anyone can do this.

Yes, and then you can't make the same reaction also attack them in an attempt to stop/hinder their casting.

You either get to identify that a spell is being cast or attack not knowing for sure if a spell is being cast.

[Contrast]

What makes you think there is a moment when counterspell is not valid anymore and the spell hasn't finished being cast?

Spoiler

Show

There Isn't

The fact that I can perceive someone casting Counterspell makes it an acceptable trigger though according to you.

Are you saying you wouldn't allow the trigger 'The enemy wizard starting to cast a spell and not being counterspelled'?

I'm honestly asking how you would resolve a player doing this as the as the answer clearly isn't time stretching into infinity as we enter a recursive loop of checking if anyone wants to counterspell, checking if the trigger has triggered, checking it anyone wants to counterspell...etc etc.

[JoeJ]

You can make an arcana check as a reaction to identify a spell being cast. Anyone can do this.

Okay. Does the text actually say this happens after the caster finishes starting to cast but before the spell is cast?

[Rukelnikov]

Yes, and then you can't make the same reaction also attack them in an attempt to stop/hinder their casting.

You either get to identify that a spell is being cast or attack not knowing for sure if a spell is being cast.

I don't wanna do the check. But my ability to do so proves, in-game, my character is aware that a spell is being cast, and can react to that situation.

[PhoenixPhyre]

Care to explain the rules of the Ready action's reaction, then?

Actions are atomic--there's no space in the flow between "player declares action" and "DM and player resolve action" unless something specifically overrides that (as an explicit exception). The Ready action does not make an explicit exception. Thus, whatever the trigger, the reaction takes place after the action that triggered it. By it's own rules.

"After the trigger" and "after the action or movement that caused the trigger to fire" are synonyms here. Because by the default rule, there is nothing in combat (the only time you can take the Ready action) that isn't an action or movement.

By the time you know he's casting a spell, it's too late to do anything about it except for counterspell. Why? Because counterspell says you can do so (as an exception to the general flow). Even taking a reaction to identify the spell lets you know what it is after the spell happens (by any reasonable reading). Which makes it not very useful for fireball, but still very useful for those less obvious spells (like dominate person).

[ProsecutorGodot]

I don't wanna do the check. But my ability to do so proves, in-game, my character is aware that a spell is being cast, and can react to that situation.

That's such a ridiculous argument that I truly do not know how to respond to it.

How does your ability to make an active check guarantee that you have already succeeded in making an active check that you are choosing not to take?

That's akin to saying "My + To Hit is high enough that I'm able to hit, anyone can roll a natural 20 as well so I'm just going to take the 20 and roll damage"

[jh12]

I never said they couldn't

Sure you did. You said you could use Silence to prevent the spell from being cast. Casting the same spell on the same turn from 21 feet away is not preventing a spell from being cast. And it doesn't seem any better than casting silence on your turn instead of waiting for theirs (much like waiting to shoot them).

[Rukelnikov]

That's such a ridiculous argument that I truly do not know how to respond to it.

How does your ability to make an active check guarantee that you have already succeeded in making an active check that you are choosing not to take?

That's akin to saying "My + To Hit is high enough that I'm able to hit, anyone can roll a natural 20 as well so I'm just going to take the 20 and roll damage"

I haven't succeeded cause I didn't even try. I don't care which spell is being cast. I only care about knowing that a spell, whichever it is, is being cast.

[Max_Killjoy]

Actions are atomic--there's no space in the flow between "player declares action" and "DM and player resolve action" unless something specifically overrides that (as an explicit exception). The Ready action does not make an explicit exception. Thus, whatever the trigger, the reaction takes place after the action that triggered it. By it's own rules.

"After the trigger" and "after the action or movement that caused the trigger to fire" are synonyms here. Because by the default rule, there is nothing in combat (the only time you can take the Ready action) that isn't an action or movement.

By the time you know he's casting a spell, it's too late to do anything about it except for counterspell. Why? Because counterspell says you can do so (as an exception to the general flow). Even taking a reaction to identify the spell lets you know what it is after the spell happens (by any reasonable reading). Which makes it not very useful for fireball, but still very useful for those less obvious spells (like dominate person).

If you have time to cast Counterspell, why don't have you have time to do anything else... other than "because the rules said so"?

[Rukelnikov]

Actions are atomic--there's no space in the flow between "player declares action" and "DM and player resolve action" unless something specifically overrides that (as an explicit exception). The Ready action does not make an explicit exception. Thus, whatever the trigger, the reaction takes place after the action that triggered it. By it's own rules.

"After the trigger" and "after the action or movement that caused the trigger to fire" are synonyms here. Because by the default rule, there is nothing in combat (the only time you can take the Ready action) that isn't an action or movement.

The rules don't say the trigger has to be movement or an action. I could choose for my trigger to be "when the tower's clock shows 12 o clock"

The rules only restriction on the trigger is that it has to be a "perceivable circumstance" and so far everyone has been deflecting the argument of how can "begins casting a spell" not be a perceivable circumstance if my character can react to it.

By the time you know he's casting a spell, it's too late to do anything about it except for counterspell. Why? Because counterspell says you can do so (as an exception to the general flow). Even taking a reaction to identify the spell lets you know what it is after the spell happens (by any reasonable reading). Which makes it not very useful for fireball, but still very useful for those less obvious spells (like dominate person).

Identifying says a spell BEING cast, if it had already finished being cast, it would have to say a spell that has been cast. Further proof is that RAI (tweeter) one player can identify the spell being cast and convey the information so that another player can counterspell it.

[Rukelnikov]

If you have time to cast Counterspell, why don't have you have time to do anything else... other than "because the rules said so"?

Where exactly?

[Max_Killjoy]

Where exactly?

Note the quotation marks -- I make no assertion that the rules say or do not say this, I'm asking a separate question about something a bit more fundamental about 5e.

[Rukelnikov]

Note the quotation marks -- I make no assertion that the rules say or do not say this, I'm asking a separate question about something a bit more fundamental about 5e.

Sry my bad, I'm having to follow like 5 different conversations already.

[PhoenixPhyre]

If you have time to cast Counterspell, why don't have you have time to do anything else... other than "because the rules said so"?

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.

[Max_Killjoy]

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.

If by default you don't have time to do anything, how do you have time to do either of those two things?

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

[ProsecutorGodot]

If you have time to cast Counterspell, why don't have you have time to do anything else... other than "because the rules said so"?

It's kind of hard to answer this question since it really is as simple as "the rules say so". With the default way that actions in combat are structured at least. Reactions have their own timings, Readied Action happens after the trigger and "beginning to cast a spell" isn't a trigger that you can respond to afterward while still having it happen "before the spell is cast". The idea that a reaction can be used in response to a "the beginning of a spell being cast" only exists in the reactions that specifically allow it.

This is something that I think the Greyhawk Initiative UA did better, where instead of having a sequential round based system is was more dynamic and allowed actions to be interrupted with pre-emptive planning rather than reactionary queues.

And of course, I feel the need to repeat, I'm perfectly okay with making exceptions if it seems appropriate. There may be a time where the situation makes sense for an arrow to successfully interrupt a spellcaster but that isn't always going to be then case. Something being able to happen doesn't guarantee that it always will happen.

If by default you don't have time to do anything, how do you have time to do either of those two things?

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

Seconds, or fractions of them as reactions are concerned. The round encompasses a time of 6 seconds total so if we're trying to adjudicate the actions of a number of creatures (I'd expect at least 6 in any given encounter) then we have to suspend our disbelief a bit on what is possible in that timeframe.

That's why features specifically alter what you're able to do in that window, such as Extra Attack making you able to strike more in a 6 second window or Quickened Spell allowing Sorcerer's to do an extended amount of spellcasting in that small window. The rules facilitate the fantasy.

[Foxydono]

This is a fun argument! I've read about half the comments and there is a fair argument to be made for both cases. My guess is that the developers intentionally left the rules very vague because they didn't want too many rules. Unfortunately, sometimes this has an adverse effect like in this case.

If I were te DM, I'd just rule what makes sense to me. And to be honest, interrupting a spell should be allowed under certain circumstances with the ready action. An action takes six seconds and so does casting most spells. I don't see a reason not to allow it at my table if they word there rdy action correctly and their plan seems plausible.

Saying you can't interrupt a spell because it doesn't state so by raw seems silly to me. Also, it's much more fun to allow it and it can be used by the DM as well of course :)