The rules also state "a character who is gagged or in an area of silence, such as one created by the silence spell, can’t cast a spell with a verbal component."
A general rule I apply to being creative is does is to not allow things that either make another feature redundent or for a spell to do the equivalent of a higher level spell.
One classic is to use create or destroy water to either remove 10 gallons of water from a creature (leaving them a shrivvelled up pile of skin and bones) or add it to their lungs so they can't breath. Power word kill is a 9th level spell!
Being able to easily hide material and somantic components and speak the vocal components so quietly noone can hear you means there is no point in taking the sorcerer subtle spell metamagic. I generally rule somantic components can not be hidden unless you are behind total cover and verbal components need ot be loud enough that anyone in the immediate vicinity (say 60ft or so) can hear.
I do not know about the rest of you but I can communicate and whisper just fine for the guy next to me to hear everything I say. And still not alert the deer standing 20 feet outside the blind.
It seems that a few like to conflate the idea of full range and tone to essentially mean a singing voice. I for one could not imagine any caster not trying as hard as possible learn how to cast quietly, in fact as quiet as possible.
Subtle spell is something entirely different than quiet. Its a total lack of verbal and somatic components, so casting quietly has no equivalence with the subtle spell ability.
If you want you could create a separate skill to quietly cast and link it to the casters level and spell level. Something like Die20 plus the casters spell bonus minus the spells level. Call it Quiet Cast.
I do not know about the rest of you but I can communicate and whisper just fine for the guy next to me to hear everything I say. And still not alert the deer standing 20 feet outside the blind.
Casting spells isn't communication, it's casting spells. The evidence we have is counterspell, and that pretty clearly implies that spellcasting is routinely visible at 60'.
I do not know about the rest of you but I can communicate and whisper just fine for the guy next to me to hear everything I say. And still not alert the deer standing 20 feet outside the blind.
Casting spells isn't communication, it's casting spells. The evidence we have is counterspell, and that pretty clearly implies that spellcasting is routinely visible at 60'.
Sorry that says nothing about seeing or hearing a spell. It states the RANGE of counterspell. The caster can still cast a spell from way outside that range and thus counterspell will not work on the Caster but might work on the area of effect.
I do not know about the rest of you but I can communicate and whisper just fine for the guy next to me to hear everything I say. And still not alert the deer standing 20 feet outside the blind.
Casting spells isn't communication, it's casting spells. The evidence we have is counterspell, and that pretty clearly implies that spellcasting is routinely visible at 60'.
1) Visible does not equal audible. One can clearly see a lot further than one can clearly hear.
2) Neither visible nor audible mean "For all spells under all environmental conditions"
3) Casting spells is clearly some form of communication, or else the sounds, tone, etc would not matter.
4) The only stated prohibition on verbal components is based on complete inability to speak clearly. There is nothing clarifying specific volume needed or how one determines that. Does someone naturally loud (say, a giant) have an easier time casting than someone naturally quieter (say, a fairy)? The rules seem to treat them as equals...
1) Exact sensory ranges have never been a hard facet of D&D
2) No, few rules perfectly describe how something would function under all possible conditions, but it sets a baseline
3) Casting a spell is not communication. Per the PHB, the words are not relevant, it's simply about causing a particular resonation with the Weave.
4) We return to the point of baselines. One could attempt to nitpick the exact meaning of what is meant by something like "a normal speaking voice", but regardless it sets a generally understood threshold of what the minimum volume would be.
3) How does 'causing a particular resonance in the weave' materially differ from 'causing a particular resonance in the ear?' Specific patterns are required for specific effects. Melodies are not words either but are nevertheless considered communication.
Um... not necessarily. To be communication you need a message, and you need a recipient for the message. Unless you assume the weave is sentient and listening to you, casting a spell isn't communication.
That is like the old 'If a tree falls in the forest and there is no one there to hear, does it make a sound?' riddle. Any given computer program is typically communicating primarily with the computer's hardware, yet the programs are still written in what is known as programming languages and are still interpreted as communications by the hardware, despite the hardware not being sentient.
I'm not sure I agree with that definition of communication, but in the end it doesn't matter whether it's communication, it matters whether it has the desired effect, and there might well be a minimum volume to be effective, which is entirely unrelated to the volume required to communicate with another person.
That is like the old 'If a tree falls in the forest and there is no one there to hear, does it make a sound?' riddle. Any given computer program is typically communicating primarily with the computer's hardware, yet the programs are still written in what is known as programming languages and are still interpreted as communications by the hardware, despite the hardware not being sentient.
I'm not sure I agree with that definition of communication, but in the end it doesn't matter whether it's communication, it matters whether it has the desired effect, and there might well be a minimum volume to be effective, which is entirely unrelated to the volume required to communicate with another human.
Oh, there very might be, but 'Loud enough to be heard within Counterspell distance' seems pulled out arbitrarily, especially without discussion of under what conditions it has to be that loud. If nothing else, consider the Invisibility spell. Do you really have to loudly exclaim 'I'm going invisible now!!!' (even if in some arcane Weave-ese) to so conceal yourself?
Possibly. I mean, you will presumably be moving after casting the spell, so it doesn't really change any practical effect or application of the spell.
Since the verbal components of spellcasting by themselves aren't directly relevant to counterspell, I suppose this whole discussion comes down to who is alerted by verbal spellcasting near the spellcaster and from what distance. My take is that as long as the verbal components are loud enough not to be considered subtle, I'm ready to consider it at the table.
Suppose a spell caster has successfully hidden from a group of enemies and is the maximum distance away for a fireball spell (150 feet)...is it possible the spell caster gets this off as a surprise round?
Or does the verbal component in this situation immediately call for initiative?
Suppose a spell caster has successfully hidden from a group of enemies and is the maximum distance away for a fireball spell (150 feet)...is it possible the spell caster gets this off as a surprise round?
Or does the verbal component in this situation immediately call for initiative?
Thanks.
There's no such thing as a surprise round. Typically, any hostile action immediately calls for initiative. But, if the caster has successfully hidden, then the group of enemies will be surprised after initiative is rolled. I recommend brushing up on the surprise rules.
Oh, there very might be, but 'Loud enough to be heard within Counterspell distance' seems pulled out arbitrarily, especially without discussion of under what conditions it has to be that loud. If nothing else, consider the Invisibility spell. Do you really have to loudly exclaim 'I'm going invisible now!!!' (even if in some arcane Weave-ese) to so conceal yourself?
There is no exception for 'V but no S or M' in Counterspell or in the rules for detectability in XGTE, so yeah, audible at 60' seems like a fair assumption.
Suppose a spell caster has successfully hidden from a group of enemies and is the maximum distance away for a fireball spell (150 feet)...is it possible the spell caster gets this off as a surprise round?
Or does the verbal component in this situation immediately call for initiative?
It immediately calls for initiative but the enemies are surprised.
Suppose a spell caster has successfully hidden from a group of enemies and is the maximum distance away for a fireball spell (150 feet)...is it possible the spell caster gets this off as a surprise round?
Or does the verbal component in this situation immediately call for initiative?
Thanks.
There's no such thing as a surprise round. Typically, any hostile action immediately calls for initiative. But, if the caster has successfully hidden, then the group of enemies will be surprised after initiative is rolled. I recommend brushing up on the surprise rules.
Thank you so much for the suggestion of brushing up on the rules.
However, in reading these rules again it mentions "If you’re surprised, you can’t move or take an action on your first turn of the combat, and you can’t take a reaction until that turn ends."
So I believe we are just mixing words that mean the same thing. Those surprised essentially lose their turn that round...aka the surprise round for them. Depending on initiatives rolled, those surprised may get attacked again before they ever get to do anything.
Oh, there very might be, but 'Loud enough to be heard within Counterspell distance' seems pulled out arbitrarily, especially without discussion of under what conditions it has to be that loud. If nothing else, consider the Invisibility spell. Do you really have to loudly exclaim 'I'm going invisible now!!!' (even if in some arcane Weave-ese) to so conceal yourself?
There is no exception for 'V but no S or M' in Counterspell or in the rules for detectability in XGTE, so yeah, audible at 60' seems like a fair assumption.
Suppose a spell caster has successfully hidden from a group of enemies and is the maximum distance away for a fireball spell (150 feet)...is it possible the spell caster gets this off as a surprise round?
Or does the verbal component in this situation immediately call for initiative?
It immediately calls for initiative but the enemies are surprised.
Doesn't that strongly imply detection is not simply automatic?
It implies that detection uses the rules in the prior section, which tells us that that detection doesn't occur if the spell has no components (due to subtle spell or creature powers).
Most tables disregard the Xanathar's rules on recognizing a spell and go with a simple "caster declares what spell they're casting, and all players are free to act on their meta understanding of the spell when deciding if they want to counter it". The other way just bogs down combat or gets hostile situations where everyone is trying to avoid revealing what they cast until the other side has missed their chance to counter.
Doesn't that strongly imply detection is not simply automatic?
It implies that detection uses the rules in the prior section, which tells us that that detection doesn't occur if the spell has no components (due to subtle spell or creature powers).
Which is not the same as 'Detection automatically occurs if there are spell components.'
It is like saying "If no one is driving, there are no traffic collisions." That does not equate to "Driving guarantees a traffic collision."
Subtle spell effectively means that a spell is cast without Somatic or Verbal components - The name is the only part that implies the casting might be imperceptible to mundane notice but the description doesn't ensure that and avoiding Somatic and Verbal components has wider uses such as casting a Verbal spell in a sphere of silence or casting a somatic spell without a free hand. Just because you have a material component doesn't mean you need to wave it around either unless the spell specifically requires you to (such as with a held weapon that is the material component used to make an attack with the spell). Obviously if the spell does something noticeable then that will be picked up, but the actual casting of it is up for debate.
On the Xanathar rule, Jeremy has confirmed RAW and RAI that also you might see a spell being cast and decide to counter it, but you don't actually know what they're casting unless you use reaction to make an arcana check and then you don't have a reaction to counter it. So if the DM (and players) are playing this way, any casting should first note that its being cast and ask if anyone wants to react to the casting (which could be the arcana test to assess the spell, counter spell or a mage slayer reaction attack), once it's confirmed that no reaction is used, then the player or DM should say what spell is being cast: https://twitter.com/JeremyECrawford/status/928766415263252480
As The_Ace_of_Rogues notes, the majority of tables out there don't use those rules though and everyone is simply presumed to know what spell is being cast and can determine if they take a reaction to that specific spell.
For the 60' rule from counterspell, remember that the reaction condition for counterspell is "which you take when you see a creature within 60 feet of you casting a spell". Arguably a deaf character can still see lips moving and cast counterspell. The other consideration is some of the Thief - Arcane Trickster's abilities such as "Magical Ambush" which causes a creature to have disadvantage on a saving throw versus the spell if you cast the spell while hidden.
About the only guidance Jeremy has given is: "Do you notice a spell being cast? The answer is based on whether you noticed any of the spellcasting components: V, S, or M."
---So Jeremy doesn't say the V, S or M components are automatically noticed or obvious. He begs the question which suggests circumstances and active work to detect can factor in. For confirmation and better guidance, Sage Advice writes:
Do you always know when you’re under the effect of a spell?
You’re aware that a spell is affecting you if it has a perceptible effect or if its text says you’re aware of it (see PHB , under “Targets”). Most spells are obvious. For example, fireball burns you, cure wounds heals you, and command forces you to suddenly do something you didn’t intend. Certain spells are more subtle, yet you become aware of the spell at a time specified in the spell’s description. Charm person and detect thoughts are examples of such spells.
Some spells are so subtle that you might not know you were ever under their effects. A prime example of that sort of spell is suggestion. Assuming you failed to notice the spellcaster casting the spell, you might simply remember the caster saying, “The treasure you’re looking for isn’t here. Go look for it in the room at the top of the next tower.” You failed your saving throw, and off you went to the other tower, thinking it was your idea to go there. You and your companions might deduce that you were beguiled if evidence of the spell is found. It’s ultimately up to the DM whether you discover the presence of inconspicuous spells. Discovery usually comes through the use of skills like Arcana, Investigation, Insight, and Perception or through spells like detect magic.
---So there we have "Suggestion" as an example with Verbal component and Sage Advice regards it as a "inconspicuous spell", but when it notes that most spells are obvious it only gives the effect of some spells as examples rather than the casting of it. Also from Sage Advice:
Is the sentence of suggestion in the suggestion spell the verbal component, or is the verbal component separate?
Verbal components are mystic words, not normal speech. The spell’s suggestion is an intelligible utterance that is separate from the verbal component. The command spell is the simplest example of this principle. The utterance of the verbal component is separate from, and precedes, any verbal utterance that would bring about the spell’s effect.
--- Which means that if you had Suggestion cast on you then the caster made some intelligible utterance of mystic words, not normal speech, just before making the suggestion. So if someone casts suggestion on you, during a conversation that the other party members are there for, they could easily notice this strange set of words. But, it notes that its all up to the DM to decide and gives the set of skills, including ones with passive values such as Insight and Perception.
Take also the Message spell which lets you whisper something to someone without being heard. This spell has V, S, M and specifies that you point at the recipient. Granted, they would have to do an Arcana check to know you're using the Message spell, but you're performing a spell you likely don't want noticed in a situation where there are people around that make you want to communicate secretly and pointing to exactly who it involves.
Ultimately, I think the sage advice note of "It’s ultimately up to the DM whether you discover the presence of inconspicuous spells" is the best advice to follow for each table and then its a matter of understanding that a spell with an inconspicuous effect would rely on circumstances and other factors to be noticed. In combat, the combatants are watching out for the hostiles they can see and thats how you argue noticing a casting that isn't subtle as occurring for counterspell. In an area with plenty of people talking and mumbling, such as a marketplace or tavern, you could miss or not hear verbal spells when you're not actively monitoring and making perception or investigation hearing checks to pick it up. On the other hand, if they're directly talking to you and cast suggestion while other party members are part of the conversation, they would likely notice just by passive insight that something was cast (unless they're storm troopers and don't question why one of them suddenly insists that these aren't the droids they're looking for). If you're in a dead quiet room and someone casts with a Verbal component, it'd be pretty hard to argue that passive perception doesn't pick up the noise but maybe you'd require an active insight check to determine its spellcasting rather than talking or mumbling. Likewise, if its only a somatic component then an NPC alone in a room that has nothing overly distracting for the PCs to check out, likely can't get away without someone noticing their gestures. But again, it might be a DM simply telling a non caster PC they notice the player making some strange gestures or movements and tell them they'd have to actively make an insight check to determine what they're doing, or a spell caster would immediately recognise a spell casting and require an arcana check reaction to determine what spell or be given an opportunity to cast counterspell if they have it.
Most tables disregard the Xanathar's rules on recognizing a spell and go with a simple "caster declares what spell they're casting, and all players are free to act on their meta understanding of the spell when deciding if they want to counter it". The other way just bogs down combat or gets hostile situations where everyone is trying to avoid revealing what they cast until the other side has missed their chance to counter.
Does that work with everything non-magically subtle? If not, why not? And what is the point of perception skill if everything is automatically perceived ?
The truth is that it is relatively rare that the other party is able to conceal their casting. Somatic components are visual and, depending on the spell, likely more easily noticed at distance.
As I said, the specific Xanathar's rules about recognizing what spell is being cast are typically disregarded because otherwise it can produce adversarial attitudes whenever there's the potential for Counterspelling, and regardless it would just bog down combat to interrupt a cast to make an Arcana check. That is the only context I'm speaking to here. Nothing to do with general application of perceptions, only the implementation- or rather non-implementation- of a particular supplemental rule.
Does that work with everything non-magically subtle? If not, why not? And what is the point of perception skill if everything is automatically perceived ?
Perception skill lets you resist skills like stealth and sleight of hand. The problem is that both of those are actions, and thus incompatible the cast a spell action.
Does that work with everything non-magically subtle? If not, why not? And what is the point of perception skill if everything is automatically perceived ?
Perception skill lets you resist skills like stealth and sleight of hand. The problem is that both of those are actions, and thus incompatible the cast a spell action.
A caster who is also a thief could do slight of hand as a bonus action, though... And even though using slight of hand (or use an object) are usually actions, they are not necessarily always such. Anyone attacking with a weapon is using an object, namely the weapon. Ditto anyone using tools. And picking a pocket is also using an object, namely the item(s) being stolen. These are all clear examples as to how these actions can be used to facilitate other simultaneous actions, as means to carry out other actions.
A perfect example might be the Arcane Trickster's "Mage Hand Legerdemain" that specifies you can cast the "Mage Hand" cantrip and use it to retrieve or place an object on someone, without being noticed if you pass a Dexterity (Sleight of Hand) check against the creature's Wisdom (Perception) check.
Following my comment: "It’s ultimately up to the DM whether you discover the presence of inconspicuous spells" - In combat, the combatants are watching out for the hostiles they can see and thats how you argue noticing a casting that isn't subtle as occurring for Counterspell
A player might specify that they want to cast a spell, in combat, without being noticed. A DM could determine that in combat it's simply not possible without using the sorcerer's Subtle ability to subdue the spell's V and/or S, Alternatively a DM could require a check such as Charisma (Deception) or even Charisma (Performance) for the player to cast a spell in a way that isn't noticeable. to streamline things the DM could determine a DC to beat rather than pitch them against combatant's Wisdom (Insight) or Wisdom (Perception). An example might be to set the DC as 8 + (the spell level times the number of components), so the DC to cast Lvl1 Command with only the "V" component, without being noticed would be DC9, but trying to cast Lvl3 Fireball with V, S and M components, without being noticed would be 8 + (lvl3 x 3 components) = DC17. Obviously a great fireball smashing them will be noticed but if the casting isn't noticed then it won't invite reactions. How would a DM temper a ruling like this from becoming something the casters do every time in combat? Tell them a failed roll means the spell fails and their action is used, not simply that the spell is noticed. Players will then weigh advantages of trying to cast inconspicuously in combat against possible failure to cast at all.
If the DM determines that such things are only possible outside of combat then again it's their decision if the casting is noticed. Message seems like an obvious spell that shouldn't be noticed, but if the caster is in close conversation with others at a table and doesn't wish to be noticed casting the Message spell at someone across the room, the DM could call for a Charisma (Deception) check against the table group's passive Wisdom (perception) or Wisdom (insight). A DM might even add +5 or more to the DC if someone at the table is a caster or have them face an active opposing check if the table's group are wary. Even if the casting is noticed, that doesn't mean they know "Message" was cast and further Charisma (Deception) checks could be made to explain it away as a Prestidigitation spell to cool their ale or that they innocently cast Message to talk to a friend across the room without shouting.
Noticing a spell casting, or it's effects, in a combat situation can be important for other reasons than counterspell. If you cast command on a bandit captain and tell him to flee, it might cause the other bandits to notice and retreat with them. But if the bandits notice their captain is fleeing under the influence of a spell rather than in terror or to retreat, they could ignore it and keep up the offence (in another situation my group was attacked by wolves and dire wolves led by a winter wolf, the wizard cast Command and told it to flee in Giant language and the other wolves followed because it was their alpha. Obviously no check was required because wolves and dire wolves wouldn't be capable of discerning a spell like Command had been cast).
The rules also state "a character who is gagged or in an area of silence, such as one created by the silence spell, can’t cast a spell with a verbal component."
A general rule I apply to being creative is does is to not allow things that either make another feature redundent or for a spell to do the equivalent of a higher level spell.
One classic is to use create or destroy water to either remove 10 gallons of water from a creature (leaving them a shrivvelled up pile of skin and bones) or add it to their lungs so they can't breath. Power word kill is a 9th level spell!
Being able to easily hide material and somantic components and speak the vocal components so quietly noone can hear you means there is no point in taking the sorcerer subtle spell metamagic. I generally rule somantic components can not be hidden unless you are behind total cover and verbal components need ot be loud enough that anyone in the immediate vicinity (say 60ft or so) can hear.
I do not know about the rest of you but I can communicate and whisper just fine for the guy next to me to hear everything I say. And still not alert the deer standing 20 feet outside the blind.
It seems that a few like to conflate the idea of full range and tone to essentially mean a singing voice. I for one could not imagine any caster not trying as hard as possible learn how to cast quietly, in fact as quiet as possible.
Subtle spell is something entirely different than quiet. Its a total lack of verbal and somatic components, so casting quietly has no equivalence with the subtle spell ability.
If you want you could create a separate skill to quietly cast and link it to the casters level and spell level. Something like Die20 plus the casters spell bonus minus the spells level. Call it Quiet Cast.
Casting spells isn't communication, it's casting spells. The evidence we have is counterspell, and that pretty clearly implies that spellcasting is routinely visible at 60'.
Sorry that says nothing about seeing or hearing a spell. It states the RANGE of counterspell. The caster can still cast a spell from way outside that range and thus counterspell will not work on the Caster but might work on the area of effect.
1) Exact sensory ranges have never been a hard facet of D&D
2) No, few rules perfectly describe how something would function under all possible conditions, but it sets a baseline
3) Casting a spell is not communication. Per the PHB, the words are not relevant, it's simply about causing a particular resonation with the Weave.
4) We return to the point of baselines. One could attempt to nitpick the exact meaning of what is meant by something like "a normal speaking voice", but regardless it sets a generally understood threshold of what the minimum volume would be.
Um... not necessarily. To be communication you need a message, and you need a recipient for the message. Unless you assume the weave is sentient and listening to you, casting a spell isn't communication.
I'm not sure I agree with that definition of communication, but in the end it doesn't matter whether it's communication, it matters whether it has the desired effect, and there might well be a minimum volume to be effective, which is entirely unrelated to the volume required to communicate with another person.
Possibly. I mean, you will presumably be moving after casting the spell, so it doesn't really change any practical effect or application of the spell.
Since the verbal components of spellcasting by themselves aren't directly relevant to counterspell, I suppose this whole discussion comes down to who is alerted by verbal spellcasting near the spellcaster and from what distance. My take is that as long as the verbal components are loud enough not to be considered subtle, I'm ready to consider it at the table.
"Not all those who wander are lost"
So a question in regards to this discussion.
Suppose a spell caster has successfully hidden from a group of enemies and is the maximum distance away for a fireball spell (150 feet)...is it possible the spell caster gets this off as a surprise round?
Or does the verbal component in this situation immediately call for initiative?
Thanks.
There's no such thing as a surprise round. Typically, any hostile action immediately calls for initiative. But, if the caster has successfully hidden, then the group of enemies will be surprised after initiative is rolled. I recommend brushing up on the surprise rules.
There is no exception for 'V but no S or M' in Counterspell or in the rules for detectability in XGTE, so yeah, audible at 60' seems like a fair assumption.
It immediately calls for initiative but the enemies are surprised.
Thank you so much for the suggestion of brushing up on the rules.
However, in reading these rules again it mentions "If you’re surprised, you can’t move or take an action on your first turn of the combat, and you can’t take a reaction until that turn ends."
So I believe we are just mixing words that mean the same thing. Those surprised essentially lose their turn that round...aka the surprise round for them. Depending on initiatives rolled, those surprised may get attacked again before they ever get to do anything.
Thanks.
It implies that detection uses the rules in the prior section, which tells us that that detection doesn't occur if the spell has no components (due to subtle spell or creature powers).
Most tables disregard the Xanathar's rules on recognizing a spell and go with a simple "caster declares what spell they're casting, and all players are free to act on their meta understanding of the spell when deciding if they want to counter it". The other way just bogs down combat or gets hostile situations where everyone is trying to avoid revealing what they cast until the other side has missed their chance to counter.
Subtle spell effectively means that a spell is cast without Somatic or Verbal components - The name is the only part that implies the casting might be imperceptible to mundane notice but the description doesn't ensure that and avoiding Somatic and Verbal components has wider uses such as casting a Verbal spell in a sphere of silence or casting a somatic spell without a free hand. Just because you have a material component doesn't mean you need to wave it around either unless the spell specifically requires you to (such as with a held weapon that is the material component used to make an attack with the spell). Obviously if the spell does something noticeable then that will be picked up, but the actual casting of it is up for debate.
On the Xanathar rule, Jeremy has confirmed RAW and RAI that also you might see a spell being cast and decide to counter it, but you don't actually know what they're casting unless you use reaction to make an arcana check and then you don't have a reaction to counter it. So if the DM (and players) are playing this way, any casting should first note that its being cast and ask if anyone wants to react to the casting (which could be the arcana test to assess the spell, counter spell or a mage slayer reaction attack), once it's confirmed that no reaction is used, then the player or DM should say what spell is being cast: https://twitter.com/JeremyECrawford/status/928766415263252480
As The_Ace_of_Rogues notes, the majority of tables out there don't use those rules though and everyone is simply presumed to know what spell is being cast and can determine if they take a reaction to that specific spell.
For the 60' rule from counterspell, remember that the reaction condition for counterspell is "which you take when you see a creature within 60 feet of you casting a spell". Arguably a deaf character can still see lips moving and cast counterspell. The other consideration is some of the Thief - Arcane Trickster's abilities such as "Magical Ambush" which causes a creature to have disadvantage on a saving throw versus the spell if you cast the spell while hidden.
About the only guidance Jeremy has given is: "Do you notice a spell being cast? The answer is based on whether you noticed any of the spellcasting components: V, S, or M."
---So Jeremy doesn't say the V, S or M components are automatically noticed or obvious. He begs the question which suggests circumstances and active work to detect can factor in. For confirmation and better guidance, Sage Advice writes:
Do you always know when you’re under the effect of a spell?
You’re aware that a spell is affecting you if it has a perceptible effect or if its text says you’re aware of it (see PHB , under “Targets”). Most spells are obvious. For example, fireball burns you, cure wounds heals you, and command forces you to suddenly do something you didn’t intend. Certain spells are more subtle, yet you become aware of the spell at a time specified in the spell’s description. Charm person and detect thoughts are examples of such spells.
Some spells are so subtle that you might not know you were ever under their effects. A prime example of that sort of spell is suggestion. Assuming you failed to notice the spellcaster casting the spell, you might simply remember the caster saying, “The treasure you’re looking for isn’t here. Go look for it in the room at the top of the next tower.” You failed your saving throw, and off you went to the other tower, thinking it was your idea to go there. You and your companions might deduce that you were beguiled if evidence of the spell is found. It’s ultimately up to the DM whether you discover the presence of inconspicuous spells. Discovery usually comes through the use of skills like Arcana, Investigation, Insight, and Perception or through spells like detect magic.
---So there we have "Suggestion" as an example with Verbal component and Sage Advice regards it as a "inconspicuous spell", but when it notes that most spells are obvious it only gives the effect of some spells as examples rather than the casting of it. Also from Sage Advice:
Is the sentence of suggestion in the suggestion spell the verbal component, or is the verbal component separate?
Verbal components are mystic words, not normal speech. The spell’s suggestion is an intelligible utterance that is separate from the verbal component. The command spell is the simplest example of this principle. The utterance of the verbal component is separate from, and precedes, any verbal utterance that would bring about the spell’s effect.
--- Which means that if you had Suggestion cast on you then the caster made some intelligible utterance of mystic words, not normal speech, just before making the suggestion. So if someone casts suggestion on you, during a conversation that the other party members are there for, they could easily notice this strange set of words. But, it notes that its all up to the DM to decide and gives the set of skills, including ones with passive values such as Insight and Perception.
Take also the Message spell which lets you whisper something to someone without being heard. This spell has V, S, M and specifies that you point at the recipient. Granted, they would have to do an Arcana check to know you're using the Message spell, but you're performing a spell you likely don't want noticed in a situation where there are people around that make you want to communicate secretly and pointing to exactly who it involves.
Ultimately, I think the sage advice note of "It’s ultimately up to the DM whether you discover the presence of inconspicuous spells" is the best advice to follow for each table and then its a matter of understanding that a spell with an inconspicuous effect would rely on circumstances and other factors to be noticed. In combat, the combatants are watching out for the hostiles they can see and thats how you argue noticing a casting that isn't subtle as occurring for counterspell. In an area with plenty of people talking and mumbling, such as a marketplace or tavern, you could miss or not hear verbal spells when you're not actively monitoring and making perception or investigation hearing checks to pick it up. On the other hand, if they're directly talking to you and cast suggestion while other party members are part of the conversation, they would likely notice just by passive insight that something was cast (unless they're storm troopers and don't question why one of them suddenly insists that these aren't the droids they're looking for). If you're in a dead quiet room and someone casts with a Verbal component, it'd be pretty hard to argue that passive perception doesn't pick up the noise but maybe you'd require an active insight check to determine its spellcasting rather than talking or mumbling. Likewise, if its only a somatic component then an NPC alone in a room that has nothing overly distracting for the PCs to check out, likely can't get away without someone noticing their gestures. But again, it might be a DM simply telling a non caster PC they notice the player making some strange gestures or movements and tell them they'd have to actively make an insight check to determine what they're doing, or a spell caster would immediately recognise a spell casting and require an arcana check reaction to determine what spell or be given an opportunity to cast counterspell if they have it.
As I said, the specific Xanathar's rules about recognizing what spell is being cast are typically disregarded because otherwise it can produce adversarial attitudes whenever there's the potential for Counterspelling, and regardless it would just bog down combat to interrupt a cast to make an Arcana check. That is the only context I'm speaking to here. Nothing to do with general application of perceptions, only the implementation- or rather non-implementation- of a particular supplemental rule.
Perception skill lets you resist skills like stealth and sleight of hand. The problem is that both of those are actions, and thus incompatible the cast a spell action.
A perfect example might be the Arcane Trickster's "Mage Hand Legerdemain" that specifies you can cast the "Mage Hand" cantrip and use it to retrieve or place an object on someone, without being noticed if you pass a Dexterity (Sleight of Hand) check against the creature's Wisdom (Perception) check.
Following my comment: "It’s ultimately up to the DM whether you discover the presence of inconspicuous spells" - In combat, the combatants are watching out for the hostiles they can see and thats how you argue noticing a casting that isn't subtle as occurring for Counterspell
A player might specify that they want to cast a spell, in combat, without being noticed. A DM could determine that in combat it's simply not possible without using the sorcerer's Subtle ability to subdue the spell's V and/or S,
Alternatively a DM could require a check such as Charisma (Deception) or even Charisma (Performance) for the player to cast a spell in a way that isn't noticeable. to streamline things the DM could determine a DC to beat rather than pitch them against combatant's Wisdom (Insight) or Wisdom (Perception). An example might be to set the DC as 8 + (the spell level times the number of components), so the DC to cast Lvl1 Command with only the "V" component, without being noticed would be DC9, but trying to cast Lvl3 Fireball with V, S and M components, without being noticed would be 8 + (lvl3 x 3 components) = DC17. Obviously a great fireball smashing them will be noticed but if the casting isn't noticed then it won't invite reactions. How would a DM temper a ruling like this from becoming something the casters do every time in combat? Tell them a failed roll means the spell fails and their action is used, not simply that the spell is noticed. Players will then weigh advantages of trying to cast inconspicuously in combat against possible failure to cast at all.
If the DM determines that such things are only possible outside of combat then again it's their decision if the casting is noticed. Message seems like an obvious spell that shouldn't be noticed, but if the caster is in close conversation with others at a table and doesn't wish to be noticed casting the Message spell at someone across the room, the DM could call for a Charisma (Deception) check against the table group's passive Wisdom (perception) or Wisdom (insight). A DM might even add +5 or more to the DC if someone at the table is a caster or have them face an active opposing check if the table's group are wary. Even if the casting is noticed, that doesn't mean they know "Message" was cast and further Charisma (Deception) checks could be made to explain it away as a Prestidigitation spell to cool their ale or that they innocently cast Message to talk to a friend across the room without shouting.
Noticing a spell casting, or it's effects, in a combat situation can be important for other reasons than counterspell. If you cast command on a bandit captain and tell him to flee, it might cause the other bandits to notice and retreat with them. But if the bandits notice their captain is fleeing under the influence of a spell rather than in terror or to retreat, they could ignore it and keep up the offence (in another situation my group was attacked by wolves and dire wolves led by a winter wolf, the wizard cast Command and told it to flee in Giant language and the other wolves followed because it was their alpha. Obviously no check was required because wolves and dire wolves wouldn't be capable of discerning a spell like Command had been cast).
I would probably allow that to hide material and somatic components.