Detect Thoughts vs a spell caster

[CloakedLight]

Was replacing Detect Thoughts with Counterspell on my sorcerer when a strange interaction popped into my head.

This involves someone at the start of combat cast Detect Thoughts on a sorcerer and the sorcerer failing the save.

If the sorcerer tries to cast a subtle spell, would you rule that it can be counterspelled because the player knows he is casting the spell? As a second thought, would the player automatically know what spell is being cast because he is reading the sorcerer's mind?

Fringe case (and I'm sure its up to the GM) but i thought it was interesting to think about and wanted to share!

[nickl_2000]

At least according to my reading of the spell, the caster of detect thought would need to spend their action to read the thoughts of the creature cast upon.

I would rule that if you used your action in combat to detect the thoughts of a caster, you know what they are casting until the start of your next turn (subtle or otherwise) and would be able to counterspell against it as a reaction.

[CantigThimble]

For the Duration, you can read the thoughts of certain creatures. When you cast the spell and as your action on each turn until the spell ends, you can focus your mind on any one creature that you can see within 30 feet of you. If the creature you choose has an Intelligence of 3 or lower or doesn't speak any language, the creature is unaffected.

You initially learn the surface thoughts of the creature - what is most on its mind in that moment. As an action, you can either shift your attention to another creature's thoughts or attempt to probe deeper into the same creature's mind.

My reading of that is that once you start detecting a creature's surface thoughts you will continue to do so without spending additional actions until you choose to delve deeper or start reading a different creature's surface thoughts. I would rule that this would allow you to tell when sorcerers cast subtle spells, as well as knowing exactly what spells any spellcaster is casting and at what level.

[DeTess]

My reading of that is that once you start detecting a creature's surface thoughts you will continue to do so without spending additional actions until you choose to delve deeper or start reading a different creature's surface thoughts. I would rule that this would allow you to tell when sorcerers cast subtle spells, as well as knowing exactly what spells any spellcaster is casting and at what level.

Have you read the entire spell? It's actually got an additional mode* that involves the victim getting a save and the caster getting more detailed information, which the OP is probably referring to as they refer to a save.

Personally, I'd rule that even the base mode would allow you tot ell when someone's casting a spell (subtle or otherwise), but detailed information would require the more involved mode.


*which I only found out about after having the spell and casting it regularly for a year in a weekly game.

[Corran]

Well, even if a DM is willing to allow it, it wont work every time. That's cause the sorcerer knows that the enemy read their thoughts, so they could go for casting a totally different spell. I mean, that's a possibility too.

[CantigThimble]

Have you read the entire spell? It's actually got an additional mode* that involves the victim getting a save and the caster getting more detailed information, which the OP is probably referring to as they refer to a save.

Personally, I'd rule that even the base mode would allow you tot ell when someone's casting a spell (subtle or otherwise), but detailed information would require the more involved mode.


*which I only found out about after having the spell and casting it regularly for a year in a weekly game.

I have, but I don't think the 'delving deeper' mode is at all necessary for this. I think the delving deeper mode is only for finding thoughts they've had in the past that aren't active occupying their attention right now. If someone is casting a spell that it is definitely going to be occupying their surface thoughts.

[jiriku]

As DM, if one of my players was using detect thoughts for a surface read while an NPC caster was casting a subtle spell, I'd rule that the PC is aware that the casting is occuring and grant an Arcana check to recognize which spell is being cast. I might even give other details like who is being targeted or what the caster hopes to accomplish.

If the Arcana check was successful, I would permit a counterspell. The PC is using two third-level spell slots and concentration and a skill proficiency just to pull off this particular trick and still needs one or two successful checks. That's a substantial investment of resources with a meaningful risk of failure, and it could plausibly produce the desired result. It's also dramatic, interesting, and a clever use of the character's abilities. I'd have no problem rewarding that.

If the character's ideals or bonds relate to anything involving cleverness, trickery, or the cunning use of magic, I'd also grant inspiration the first time the player used this trick.

[FrancisBean]

This very situation came up in my group's most recent session, except that the character with Detect Thoughts active didn't have Counterspell (Bard, too low level to have Countercharm even if it didn't require an Action). Instead, she called out to the rest of the party -- "Hey, this witch is trying to cast Flesh to Stone on me!"

The assembled martial members of the party cast their version of "Counterspell." The witch went down before her next turn. :smallbiggrin: But even if she hadn't, the primary caster in the group was all set to use Counterspell because she'd been told what was coming.

[Lunali]

As DM, if one of my players was using detect thoughts for a surface read while an NPC caster was casting a subtle spell, I'd rule that the PC is aware that the casting is occuring and grant an Arcana check to recognize which spell is being cast. I might even give other details like who is being targeted or what the caster hopes to accomplish.

If the Arcana check was successful, I would permit a counterspell. The PC is using two third-level spell slots and concentration and a skill proficiency just to pull off this particular trick and still needs one or two successful checks. That's a substantial investment of resources with a meaningful risk of failure, and it could plausibly produce the desired result. It's also dramatic, interesting, and a clever use of the character's abilities. I'd have no problem rewarding that.

If the character's ideals or bonds relate to anything involving cleverness, trickery, or the cunning use of magic, I'd also grant inspiration the first time the player used this trick.

Why do you require them to know what spell it is to counter it? I understand wanting the check to know whether they want to counter it or to know what level they want to cast at to avoid a roll, but they should be allowed to cast Counterspell even without that information.

[Unoriginal]

Identifying a spell while it's being cast takes a reaction, so does Counterspell.

Even if the DM agrees that Detect Thought bypass Subtle Spell, the same character couldn't do both.

[tieren]

Identifying a spell while it's being cast takes a reaction, so does Counterspell.

Even if the DM agrees that Detect Thought bypass Subtle Spell, the same character couldn't do both.

I believe the identifying rule refers to looking at the person and trying to figure out what they are doing. I don't believe it would apply if you were already in their head listening to their thoughts.

[Ganymede]

Identify a spell while it's being cast takes a reaction, so does Counterspell...the same character [using detect thoughts] couldn't do both.

While it is true that identifying a spell while it is being cast takes a reaction, that isn't exactly material here. That reaction is an application of reasoning and memory in order to decode the words and gestures of a spell-caster.

To contrast, merely listening to something, such as a villain's mid-battle trash talk, does not require a reaction. This would seem to include listening to someone's surface thoughts via Detect Thoughts. As such, if we're going to put the identity of a spell caster's spell in the surface thoughts, it doesn't make much sense to require a reaction to hear it.

[Unoriginal]

While it is true that identifying a spell while it is being cast takes a reaction, that isn't exactly material here. That reaction is an application of reasoning and memory in order to decode the words and gestures of a spell-caster.

To contrast, merely listening to something, such as a villain's mid-battle trash talk, does not require a reaction. This would seem to include listening to someone's surface thoughts via Detect Thoughts. As such, if we're going to put the identity of a spell caster's spell in the surface thoughts, it doesn't make much sense to require a reaction to hear it.

That "if we're going to put the identity [of a spell] in the surface thought" premise is incorrect. You do not cast Fireball by repeating "fireball fireball fireball" over and over in your mind. So it is required to identify which spell the person is actually casting.

You can, however, get the idea the caster is casting a Subtle Spell via thought detection.

Same way if you're detecting the thoughts of an assassin about to do a surprise attack. The assassin's is probably not going to think "aha, I'm using the Rostin Manoeuvre to blind my target as my blade poisoned with Mudroot extract, which prevents conventional healing, does it's job". But "attack!" is probably part of their surface thoughts.

[Ganymede]

That "if we're going to put the identity [of a spell] in the surface thought" premise is incorrect. You do not cast Fireball by repeating "fireball fireball fireball" over and over in your mind. So it is required to identify which spell the person is actually casting.

It really sounds like you're putting a gameplay cost in translating rules-speak into game-speak, and vice versa.

You're right that PCs and NPCs don't think in rules terminology, but we wouldn't expect them to; PCs and NPCs think of the world in real-world terms. Our PCs aren't the ones translating these thoughts into rules-speak, we as players are. Why would we put that burden on our PCs?

Someone thinking about a big ball of fire engulfing his or her foes is enough to recognize a spell; we don't need someone to think of the literal PHB definition of the Fireball spell to do so.

[Unoriginal]

It really sounds like you're putting a gameplay cost in translating rules-speak into game-speak, and vice versa.

You're right that PCs and NPCs don't think in rules terminology, but we wouldn't expect them to; PCs and NPCs think of the world in real-world terms. Our PCs aren't the ones translating these thoughts into rules-speak, we as players are. Why would we put that burden on our PCs?

Someone thinking about a big ball of fire engulfing his or her foes is enough to recognize a spell; we don't need someone to think of the literal PHB definition of the Fireball spell to do so.

What makes you think that someone who is casting Fireball is imagining a big ball of fire engulfing their foes? and what makes you think that imaginging your foes being engulfed by fire is part of your surface thought when you're casting a spell?

Casting a spell is a complex process, which is literally different for every spellcaster. To the point that even someone who taught the spell to a student couldn't automatically identify the spell if the student was casting it.

I'll grant that Detect Thought will let someone know that the caster is attempting a Subtle Spell, and may give you a chance at identifying it. As a DM, I would probably allow the thought-detector to know who the caster is targeting.

But allowing people to know which spell is being cast without spending time to identifying it is anthetical to the thematic of magic in 5e.

That isn't to say that Detect Tought can help you pierce a caster's plan. If they think "alright I'm going to blast this adventurer with fire as soon as my grunts have attacked the big guy in armor", Detect Thought can help knowing what they plan to do. But that doesn't mean the thought-detector will know which spell is being used in detail.

[Ganymede]

But allowing people to know which spell is being cast without spending time to identifying it is anthetical to the thematic of magic in 5e.

This laughably contradictory comment, in which you laud the enigmatic thematics of magic while simultaneously asserting that an actual magical spell shouldn't let someone circumvent something ordinarily done in a mundane fashion, isn't exactly why I'm bowing out of this conversation, but it definitely played a part.

[Unoriginal]

This laughably contradictory comment, in which you laud the enigmatic thematics of magic while simultaneously asserting that an actual magical spell shouldn't let someone circumvent something ordinarily done in a mundane fashion, isn't exactly why I'm bowing out of this conversation, but it definitely played a part.

It's not contradictory. If you wanted to homebrew a "Identify Spells Which Are Being Cast" spell, then I wouldn't have any problem with it. But that is not the power of Detect Thought.

Also, there is no mundane way to circumvent subtle spell's effect of making you unable to identify spells. So Detect Thought does circumvent something. Just not what you're talking about.

[tieren]

Its just a matter of interpretation of what you consider "surface thoughts".

Some may think of that only a your internal self dialog (ie what they are saying to themselves), and I can see where those people wouldn't think the person is saying "I will cast a fireball over there, then maybe move to the left".

My personal opinion is that any intentional act, requires thought to undertake and detect thoughts would reveal that intention, so unless it was a random wild magic surge or something the detector would know what spells the detectee is choosing to cast.

[SpanielBear]

Hang on a second here. This derails the thread a bit but I’d like to clarify something- Counterspell is a reaction, right? So why do you need to spend a reaction in order to cast it (in general, I get the debate here specifically about dualling resources of subtle spell and detect thoughts). But in normal terms, surely it goes:

DM: The wizard casts x.

Player: Counterspell!

Not:

DM the wizard casts x.

Player: Counterspell!

DM: I’m sorry, but noticing he was casting used up your reaction so you can’t do anything else.

I mean I must be misunderstanding something here!?

[CloakedLight]

Hang on a second here. This derails the thread a bit but I’d like to clarify something- Counterspell is a reaction, right? So why do you need to spend a reaction in order to cast it (in general, I get the debate here specifically about dualling resources of subtle spell and detect thoughts). But in normal terms, surely it goes:

DM: The wizard casts x.

Player: Counterspell!

Not:

DM the wizard casts x.

Player: Counterspell!

DM: I’m sorry, but noticing he was casting used up your reaction so you can’t do anything else.

I mean I must be misunderstanding something here!?

Using counterspell normally means you are just countering a spell. You do not know if you countered say a Firebolt or a Fireball. You just know you countered a spell. If you want to know what spell is being cast, XGTE states that you need to use your reaction.

Edit: Didn't mean to offend anyone by bringing up XGTE. Was just mentioning it because it is how me and my group have always played (never know what the enemy is casting until seeing the after affects). I think it make sense but to each their own.

[Kane0]

And like everything else in XgtE, it is entirely optional.

Edit: How I would rule it is:

Player casts Detect Thoughts on sorcerer and gets surface thoughts, Sorcerer can possibly use reaction to counterspell. Player can attempt to delve deeper using their action later on if they wish.
Depending on circumstances as DM I may allow the sorcerer to use their action to attempt a save and shake off the effects of the spell, but only once.

Under effects of the spell, Sorcerer goes to cast a spell. This is on their mind at the time of casting regardless of Subtle Spell and thus known to the Player who can act accordingly, including using a counterspell.

Everyone else sees nothing of these magical, mental gymnastics, just a series of spells being cast and interrupted. Probably a lot of frowning too.

[PhoenixPhyre]

And like everything else in XgtE, it is entirely optional.

Technically that applies to everything, but that aside--

the presumed default is that there is no stock way of identifying spells unless those rules are in play. Before XGtE came out you could make the argument that the default was "everyone knows everything automatically", but since an explicit option was included, that largely precludes that option.

Of course with 5e there's not a problem with a group deciding otherwise. If they do, those are the rules (printed or not). But that requires an explicit decision to override the default and so cannot be reliably ported between games at different tables.

[NaughtyTiger]

"But allowing people to know which spell is being cast without spending time to identifying it is anthetical to the thematic of magic in 5e."

Prior to XGE, it did not require a reaction to ID the spell. Most DMs say, I am casting Fireball, player panics and says Counterspell!

Ergo, it isn't incompatible with the theme of magic in 5e.

Moreover, XGE added a dumb rule. (not clarifying a fuzzy rule, no, it created a rule out of whole cloth)
If i watched the bad guy cast fireball 2 rounds ago, then i should immediately recognize when he is doing the same chanting and hand gestures, and see the mote of fire building in front of him.

[Kane0]

Yeah, seeing as Xan's came out something like 3 years after the PhB I've been doing the 'know by default' much longer than 'reaction to figure out'. If it was uncertain in the past I'd do the 'roll to figure out' thing without requiring a reaction.
Personally I don't like the reaction cost, but that's neither here nor there.

[PhoenixPhyre]

Prior to XGE, it did not require a reaction to ID the spell. Most DMs say, I am casting Fireball, player panics and says Counterspell!



Not true. There was no default. In my experience, DMs only rarely said the spell that they were casting. I don't care one way or another, but I'd guess that the intent was that spells are not identifiable (with always the houserule option). From the way XGtE's passage is worded it seems that they were giving an additional option, not giving a variant restriction.

[Asmotherion]

I go for:

Spell or magical effect is about to happen;

Triggers a free arcana check to identify from proficient characters. No action needed. Kinda like a Save.

It represents how you may be familiar with Somatic and Verbal components (or Runes and other scripts on other magical effects) to at least know something magical is about to happen, and to try to predict the outcome by either A) Knowing the specific Components (Know/Have encountered the spell before) or B) Translating their meaning and intent from your Knowlage of the Arcane Arts to predict the outcome. Kinda like when you meet an unknown word in a phrase, but you can guess it's meaning by the context, as well as understanding it's root words.

It just makes more sence to me.

[NaughtyTiger]

Not true. There was no default.
I said prior to xge the specific rule is not in place.
You said. Not true, there was no specific rule.

I am confused.

[PhoenixPhyre]

I said prior to xge the specific rule is not in place.
You said. Not true, there was no specific rule.

I am confused.

You said the pre-existing rule was automatic identification. It wasn't. It was entirely up to the DM, anything from "impossible" (the way I've always seen it) to "you get a free check" to "you always know." The clear RAI was the first option. So XGtE was an extra option, not a nerf.

[Unoriginal]

"But allowing people to know which spell is being cast without spending time to identifying it is anthetical to the thematic of magic in 5e."

Prior to XGE, it did not require a reaction to ID the spell. Most DMs say, I am casting Fireball, player panics and says Counterspell!

Ergo, it isn't incompatible with the theme of magic in 5e.

Actually, prior to the Xanathar's the assumption by the writers was that it couldn't be done.

It was players who wanted to do it.


You said the pre-existing rule was automatic identification. It wasn't. It was entirely up to the DM, anything from "impossible" (the way I've always seen it) to "you get a free check" to "you always know." The clear RAI was the first option. So XGtE was an extra option, not a nerf.

More specially, Counterspell was meant to be cast "blind". That DMs told the players what the spell was wasn't the default assumption at any point. Though it was popular because players like to not have to risk wasting spell slots.


Hang on a second here. This derails the thread a bit but I’d like to clarify something- Counterspell is a reaction, right? So why do you need to spend a reaction in order to cast it (in general, I get the debate here specifically about dualling resources of subtle spell and detect thoughts). But in normal terms, surely it goes:

DM: The wizard casts x.

Player: Counterspell!

Not:

DM the wizard casts x.

Player: Counterspell!

DM: I’m sorry, but noticing he was casting used up your reaction so you can’t do anything else.

I mean I must be misunderstanding something here!?

Actually it should go:

DM: "the wizard starts casting a spell"

Player: "Counterspell!"

OR

DM: "the wizard starts casting a spell"

Player: "Which spell?"

DM: "Do you want to do a check for it? It'll eat up your reaction."


Nothing wrong with saying what the spell is without additional fuss, but it's not a feature of Counterspell.

[NaughtyTiger]

You said the pre-existing rule was automatic identification. It wasn't. It was entirely up to the DM, anything from "impossible" (the way I've always seen it) to "you get a free check" to "you always know." The clear RAI was the first option. So XGtE was an extra option, not a nerf.

BS. I said it didn't require reaction.
And most DMs...

You and Unoriginal both say it's RAI that nobody knows the spell the caster is popping off.
I haven't seen that anywhere, where did you get that?

[Mellack]

The closest thing I can think of to what I imagine casting would be like is a pianist. If you read their mind while they were playing you probably wouldn't get "Concerto #5" from them but more thoughts like "faster and louder here" or the like. So I do not think that Detect Thoughts would tell you what spell they were casting, at least not without a check. I do think it would bypass the subtle casting to tell you that they are casting a spell.

[Laserlight]

The closest thing I can think of to what I imagine casting would be like is a pianist. If you read their mind while they were playing you probably wouldn't get "Concerto #5" from them but more thoughts like "faster and louder here" or the like. So I do not think that Detect Thoughts would tell you what spell they were casting, at least not without a check. I do think it would bypass the subtle casting to tell you that they are casting a spell.

I can imagine you'd get "Aiming at that guy" or "If I drop it there, I can get all of those guys", or maybe other things -- "a giant ape" for Polymorphing an ally, or "a boulder" if that's what his Minor Illusion is going for.

XTGE's rule is rubbish because you can identify a spell with your reaction, call out to Bob "the guy in purple is casting Fireball, counter it!" and Bob cast Counterspell with his reaction...but you can't identify it and counterspell it yourself even though that would necessarily be faster than telling Bob to do it.

I'd require an Arcana check and you'd have to roll high to identify fast enough to react; but I'd be okay with "no one can identify" or "everyone can identify" or some other method, or even "Identify as per Xanathar's but you can't communicate"...although in that case your mage keeps Det Thought on your Arcane Trickster who took Expertise in Arcana, and we have a different flavor of the thread we're in.