Can a Spell cast with Subtle Spell and an Arcane Focus be Counterspelled?

Question

Recently, this question asked whether you could Counterspell a spell without a material component that completely eliminates component requirement via Subtle Spell. The answer was no, with a Crawford Tweet as evidence. The following was asked in response to the Tweet but never answered and is a situation likely to occur in a campaign I'm running:

A Sorcerer uses Subtle Spell on a no-cost material component spell like Sleep or Fireball which they cast with a small crystal Arcane Focus kept tightly gripped and hidden in their fist.

In previous editions, spell descriptions indicated how materials were to be used: sprinkling sand or rose petals for Sleep, or throwing a ball of bat guano for Fireball. 5e doesn't provide these, nor does it seem likely such usages are possible with a Spellcasting Focus.

So, in this situation, is there enough information for another spellcaster to realise a spell is being cast for them to Counterspell?

Answer 1

The Material Component of a spell only requires you to have a hand free and be able to access the arcane focus - it does not require any gestures (where the Somatic comes in) or articulations (Verbal).

Material (M)

A spellcaster must have a hand free to access these components, but it can be the same hand that he or she uses to perform somatic components. (PHB 203)

For Arcane Foci, you must only wield it to satisfy the Material component of the spell. Just as wielding a sword is not a perceptible attack, merely wielding an Arcane Focus and casting something with Subtle Spell will not make the spell perceptible.

Answer 2

If you follow Xanathar's Optional rules,

Yes, the spell could still be countered.

From XGtE, p. 85, "Perceiving a Caster at Work":

To be perceptible, the casting of a spell must involve a verbal, somatic, or material component. The form of a material component doesn’t matter for the purposes of perception, whether it’s an object specified in the spell’s description, a component pouch, or a spellcasting focus.

It's irrelevant whether the Arcane Focus is small or not, casting a spell with it makes it perceptible. The only way to make casting imperceptible is to remove the Material, Somatic and Verbal components. From XGtE, same section:

If the need for a spell’s components has been removed by a special ability, such as the sorcerer’s Subtle Spell feature or the Innate Spellcasting trait possessed by many creatures, the casting of the spell is imperceptible.

As far as I know, there is no other way to make the casting of a spell imperceptible (aside from being invisible or similar). As long as it has a spell component, it is perceivable, and thus, can be countered. Even if the spell has no components at all, it can be obvious you have cast a spell! Some spells have flashy descriptions. In Fireball, for example,

A bright streak flashes from your pointing finger to a point you choose within range

So a Subtle Sorcerer with Greater Invisibility can cast it without being perceived, but everyone will see the streak of light coming from his position. It won't be countered, but everyone will know there was a trigger happy pyromaniac around.

That being said, the DM is free to make calls where common sense applies. If an enemy is really far, if there are lots of obstacles in between (like a crowd), if the perceiver is blind, etc, all of these should be taken into account. At my table, for example, our Totem of the Eagle Barbarian can spot spells being cast from a mile away, other players cannot.

However, the rules address the OP's specific example, of using a "small Arcane Focus", and because "the form of a material component doesn’t matter for the purposes of perception", you could just as well be waving around a giant Gandalf quarterstaff.

Answer 3

RAW says absolutely nothing about whether a spell is perceptible or not if its casting requires somatic, verbal, or material components.

To be perceptible, the casting of a spell must involve a verbal, somatic, or material component.

This means that if the spellcasting is perceptible, then it involves a verbal, somatic, or material component. It does not mean that if the casting of a spell involves verbal, somatic, or material components then it is perceptible.

With this alone, if we have at least one component present we don't know anything about whether or not the casting is perceptible. What can be concluded, is that if we have no components present, then we absolutely know that the spell is imperceptible.

---

The form of a material component doesn’t matter for the purposes of perception, whether it’s an object specified in the spell’s description, a component pouch, or a spellcasting focus.

What this concludes, is that if a spell would be perceived when using one form of material component, then it would be perceived using any different form of material component; and if the spell would not be perceived when using one form of material component, it would still be unperceived if you used any other form.

---

If the need for a spell’s components has been removed by a special ability, such as the sorcerer’s Subtle Spell feature or the Innate Spellcasting trait possessed by many creatures, the casting of the spell is imperceptible.

This only supports our first conclusion, if there are no spell components used in casting the spell, then the spell is imperceptible. it doesn't say anything about whether or not the spell would have been perceptible if there was still a need for the spell's components.

---

Back to my conclusion, if the spellcasting has components, then there isn't any rule for whether the spell is perceptible or not. It is left up to the DM.

Regarding what the rules as intended are: I mentioned in one of the comments to BlueMoon93's answer that I believe the intended rules are that all spells are perceptible if their casting includes any of the three components, I take that back, with experience I believe that is how things should be played, but I do not believe those are the intended rules.

I believe that the rules intended to leave the decision, for whether a spell which requires components is perceptible or not, in the hands of the DM, and this is what RAW does, because the only rule on whether a spell is perceptible or not, is that if it doesn't have any components it is absolutely not perceptible. This is how a lot of 5e rules are, they are left open for the DM to decide. So the answer to the question of whether a spell cast with subtle spell and an arcane focus can be counterspelled, or not, is that the DM gets to decide!

WotC has made it very apparent that 5e is intended to have fewer rules and a more open interpretation of the rules. This supports the that the rules may intend for the DM to determine when a spellcasting is perceptible.

---

Even though the intent of the rules is probably to give the DM the decision for whether a spellcasting is perceptible or not, I believe this is a terrible way to play. This is my opinion formed from both experience, and from seeing the negative experiences of others.

If the DM has the choice of whether or not casting spells is perceptible, I've seen it play it out two ways:

The first way I see it play out is that the DM decides that the spellcasting from the 'clever' NPCs and enemies becomes imperceptible, and when it comes to players they need subtle spell for their spells to be imperceptible (this is frustrating to players because on the whim of the DM, counterspell isn't even an option, and in more situations it pits the DM against the players).

The other way that I see it play out is that casting subtly is treated as a skill check of some sort: deception, performance, sleight of hand, arcana even (though more rarely), and in every situation I've seen or heard of, it wasn't handled properly, and it was too easy to fool everything (everything that can counterspell at the very least, in the monster manual, mages rarely have high perception or insight, of course then DMs fudge this, but they usually still make it too easy for mages to deceive with skill checks). This slows down the game because whenever a spell is cast a contest or ability check must be made. The worst part about treating the perceptibility of casting in this way is that those who are playing the sorcerer always cry foul about their feature being downplayed because the DM ruled it, and without any written rules to rationalize their loss; in their mind a rule was just homebrewed which takes their strength and gives a little bit of it to others. I've found that even players who aren't playing sorcerer for that game, but that are fond of the sorcerer, feel hurt when they see the rules treated in this way.

Answer 4

It Could be Countered Sometimes, But it has to Actually be Detected

XGtE p. 85 (as previously quoted by BlueMoon93):

To be perceptible, the casting of a spell must involve a verbal, somatic, or material component.

Hence one or more of these components is a necessary precondition to perceiving the casting (to the extent we enforce materials in Xanathar's Guide to Everything). An arcane focus of any kind may make it possible to perceive. However it is not clear that all arcane foci under all circumstances would actually be perceived, simply that they are one of the things that make it possible to perceive.

For counterspell specifically, we see:

Casting Time: 1 reaction, which you take when you see a creature within 60 feet of you casting a spell.

It is not sufficient simply that the spell be perceptible in some way; it must actually be perceived and be perceived via the sense of sight specifically to be a valid target for counterspell.

This leads us to your "small arcane focus". If the component can be hidden from view then while in a state of being hidden from the counterspell caster they may or may not see it or the spell. The onus is on them to do so, the mere fact that an arcane focus of some sort is involved does not make them see it, it merely makes it possible.

It should require a perception roll by the counterspell caster whenever no components are being used in an obvious manner, and is only possible where visual perception is possible (eg: no greater invisibility). Counterspelling when the focus is small and easily concealed should require a perception roll, perhaps contesting a slight of hand check.

If any spell with material components was automatically perceptible and automatically visually perceptible, then one could counterspell through walls, while blind, or against invisible opponents. Components are a necessary condition, not a sufficient one.

If it was not possible to discreetly cast a spell with material components under the table, from time to time, then the question arises: Can I do anything with minor illusion whatsoever?