What do I know, when deciding whether to cast Counterspell?

Question

I'm not entirely clear on how Counterspell works, when trying to counter higher-level spells: the CS description only talks about disrupting a creature you can see, within 60 feet, casting a spell.

However, when trying to counter a higher level spell:

1. Do I know what spell is being cast?
2. Do I at least know (somehow intuit, based on VSM components) the level of the spell?
3. Or can I tell the spell/level of the spell by sensing a disturbance in The Weave? (I.e., if the spell is being cast using Subtle Spell, can I still tell what's going on?)

The point of the question is to determine how fruitful CS can be in combat--if I know what the other guy/gal is casting (or at least the level), I can decide whether I want to spend my L8 slot to counter his/her L8 slot. But if I have no idea, and I end up using a L8 slot to counter a L3 spell... seems a bit painful.

Hope this made sense!

Answer 1

It's mostly up to the DM, but Xanathar's Guide to Everything has some optional rules

In Xanathar's, Chapter 2 has a Spellcasting section that begins with:

This section expands on the spellcasting rules presented in the Player’s Handbook and the Dungeon Master’s Guide, providing clarifications and new options.

That's a little unclear as to what's a clarification vs what's a new option, but given that identifying spells isn't covered at all in the PHB or DMG, then I tend to view identification of spells as an option rather than a clarification.

Identifying a Spell states (my emphasis):

Sometimes a character wants to identify a spell that someone else is casting or that was already cast. To do so, a character can use their reaction to identify a spell as it’s being cast, or they can use an action on their turn to identify a spell by its effect after it is cast.

The specifics for how this works are listed in the book, but I'm honestly not a big fan of it because of the action cost listed above.

This is especially true for counterspell which already uses up your reaction. So if you use your reaction as stated above, then you won't be able to actual counterspell, which is pretty unsatisfactory from a player's perspective.

How we've done it at my tables

At my tables, we've tried a couple different options with varying effect. I'm not sure which I like more, so I'm going to just go ahead and discuss what we've done and let others determine if they prefer one of the ones I've used or the Xanathar's method.

You've gotta guess

In this scenario, there is no way to identify in time. You are perceiving a caster at work and throw up a counterspell to stop them. It's up to the player to determine the level of the counterspell they want to use, and they take the risk of wasting it against a cantrip or requiring an ability check if it's higher than the spell slot level they've used.

Honestly, I kind of liked this one the best. It gave you a choice to make, and one with cost. It's an in-the-moment event and if you feel that the risk was worth the reward, then you go with it.

Cost-free identification

We tried allowing an Arcana check at no cost. Similar to the system in Xanathar's, but without the reaction cost. This gave the player's more info and the ability to decide if and when to counterspell.

What's kind of nice about this is that it does create a bit more of a level playing field between PC counterspellers and NPCs. Looking at the flip side, most player's don't begin their action with "I'm casting a generic spell", they tend to state the spell they're casting. This gives the DM info that they don't necessarily provide to the players in the same way.

Being able to know each and every spell cast as it's being cast seems a bit more fair, but it also removes a lot of the potential risk.

This option is perfectly fine as well, but I did kind of like the unknown risk of my first option.

What about working as a team?

Another potential option is have two players work together. One player uses their reaction to identify, and then once identified, the 2nd casts counterspell with the additional information.

And that type of action is also going to be table dependent. This question covers some of the issues revolving around speaking outside of your turn (during a reaction in this case.)

It comes back to being up to the DM/table to decide

Whether you use the method from Xanathar's (whether optional or 'actual') or one of the systems I've tried, it's all about having fun. What works for one table and everyone enjoys it won't necessarily be the same for another table.

Talk to your group and figure out what method works. If you don't like how it ends up, you can always change it after talking about it.

Answer 2

Do I know what spell is being cast?

Not through the counter spell itself. In general, if there is a specific ability to do X, D&D 5e specifies it through keywords or description. See Specific beats general on Page 7 of the PHB or Page 4 of the D&D 5e Basic rules.

Do I at least know (somehow intuit, based on VSM components) the level of the spell?

The Arcana skill is your best candidate. Unlike spells, feats, and class abilities, the specifics of when and where the various D&D skills are applied are left to the Dungeon Master to decide. On page 175 of the PHB and is 74 of the D&D 5e Basic rules state that the every tasks a character or monster may attempt is covered by one of the six abilities. The following section lists suggested specifics but it is not meant to be taken as a definitive list of everything a character can attempt in game.

The assumed default is the player to describe what they are doing, and the referee comes up with the rulings to resolve it. Sometime this means saying no if it the action is impossible given the circumstance or the amount of time.

Or can I tell the level of the spell by sensing a disturbance in The Weave?

This is considered flavor text and is left completely in the Dungeon Masters to describe how the various ability checks manifest in his campaign. Some would opt for a mundane description, other would do as you did above and use various bits of background to spice up their description.

My advice

To make a ruling you need to consider is how long the identification takes. If you consider it like a search then it would require a character spend his action on his turn to figure out what was cast. If you consider it to be quicker then you may be comfortable in letting a spell identification check occur during the reaction.

You can use the box labeled Improvising an Action on page 193 of the PHB or Page 72 of the Basic rules for guidance in deciding how to handle the check.

My personal opinion is that I would allow a check but the character would have a very high DC of 25 to ID the spell during a reaction. If they get a 20 or higher they get one piece of information during the reaction. Otherwise they just have to cast the counterspell knowing only that a spell is being cast. If done as part of their normal turn I would drop it down to DCs of 15 and 20.

Another suggestion I have is that you could opt to fully describe the material component being used and allow player skill to come into play. I would do this anyway as I find the various description of material components evocative.

Answer 3

An unofficial tweet by rules designer Jeremy Crawford describes how he would adjudicate this situation (though it is not a ruling, per se):

As DM, I let you ID a spell if you know it (or it's on your class's spell list) and if you perceive V, S, or M.

Answer 4

There aren't explicit rules for this. The description for Counterspell doesn't say, and there's no guidance under Intelligence (Arcana).

I'm pretty sure this is intentional. D&D 3.x had a "Spellcraft" skill which was specifically used to do this (DC of 15 + spell level, although as with monster identification, I'm not completely keen on that, since it seems like some big famous spells might be easily recognized even by people who can't cast them). This is also because that edition has a general counterspell rule (any spell can be cast as its own counter). By contrast, 4E (by design) didn't have a counterspell mechanic, and apparently correspondingly didn't offer a way to identify spells as they are cast, although in my experience many people play 4E in a very "game-forward" way, with everyone's powers known to everyone automatically as they are used.

I think different groups find it fun to play this in different ways, and so it's left open. Making an Intelligence (Arcana) check based on observation of verbal, somatic, and material components makes sense, but exactly how hard it should be is left to the group. In another answer here, RS Conley suggests a "Very Hard" difficulty class of 25 to identify the spell during a reaction; I'd be inclined to make that much lower — a Medium DC of 15, say. If I were really on the ball, I might lower the DC on the fly for spells on the character's own known list. And, venturing into house rule territory, I might give characters with Wizard levels advantage on the checks — all that institutional learning is good for something.

But again, all of that is open. The game could certainly be played as if each spell is unique each time it is cast, with no possibility of an observer guessing — in that case, Counterspell either works or it doesn't.

(Also in the category of house rules: the spell description says that you can take the reaction when you see a creature casting a spell. I would probably also allow it if you heard a spell's verbal components in a dark room.)

Answer 5

Personally, I would be surprised if this isn't a topic elaborated upon in the DMG. In the meantime, however, here's what I've been doing with my players:

First of all, the whole debate comes down to the question "Can I intuit anything about spells another individual is casting?" As a DM, I've been allowing players to use an Intelligence (Arcana) check to determine certain properties about a spell. Restrictions to the check are that the player in question must aware of the casting and not incapacitated. Furthermore, any loss of senses gives the player disadvantage on the roll. I do allow the check to be a part of the reaction/casting process for Counterspell The DC is not fixed for the check, but instead based on thresholds as follows:

Result of 10 or better - Player learns the spell's school

Result of 15 or better - Player learns the spell's base level

Result of 20 or better - Player learns the exact spell name

Result of 25 or better - Player learns the exact level at which the spell is being cast

I would also like to point out that nowhere in any D&D text does it indicate that somatic or verbal spell components are the same from class to class, (or species to species for that matter) even for the same spell. So a wizard's fireball might look and sound completely different from the same spell coming from a Light-domain cleric. Thus, I hesitate to give any advantage to the Intelligence (Arcana) check based on class. Instead, I explain it to my players as though the Counterspell-caster is somehow interpreting the flow of magical energies.

With regard to your last point, about trying to determine the efficacy of Counterspell in combat, as a player I personally only cast it at Lv 3. Augmenting the level of Counterspell confers no advantage on the ability check to manually counter the spell, and I've found that the Lucky Feat gives me a great edge in that regard. That being said, I would consider changing this strategy once I begin encountering Lv8+ spells regularly, as those are less likely to be countered manually even with a re-roll.

Answer 6

The short answer:

1. You would know what spell is being cast if you have learned the spell or are familiar to seeing it cast. Otherwise, the spell would not be revealed (unless your DM decrees otherwise). Your DM might also make a house rule allowing you to take an Arcana check to discover the school, components, level, or other attributes of the spell. You may be able to determine the spell, but the CS spell itself cannot.

2. Again if you are familiar with the spell and/or have learned it you would recognize it. If not, again this is just up to your DM and Arcana checks. If I was DMing this I would allow you to roll either Arcana to determine attributes of the spell or Perception to attempt to recognize danger the spell might present to you.

3. If I was DMing this and the spell in question was being cast using Subtle Spell, I would most likely either have them roll Arcana/Perception with disadvantage, or more likely, subtract 1d4 from whatever they roll for their check. Again, this is honestly just up to your DM but you could attempt to ask your DM how they feel about this.

Depending on how your DM decrees on this, CS is an incredibly useful spell for not dying to some giant spell.