D&D 5E Can a caster tell if someone saved or not against their spell?

[Blue]

Is there a definitive rule if a caster knows if a target succeeded on a save or not?

The example that came up is someone (a bard) cast Charm Person, which has no visible effect when cast. The target (an enchanter wizard who also has the spell) identified the spell as it was being cast, saved, and acted friendly.

Outside of other checks (deception vs. insight, etc.) is there any inherent knowledge by the caster if the spell save was successful or not in the rules? There was in some earlier editions, but 5e is it's own definition.

Another example could be several targets in fireball, and one takes half damage thanks to fire resistance, not a successful save. Outside other checks, would the caster inherently know that target had failed their save?

 

[Blue]

Can we return to the question about casters knowing saves instead of a threadjacking about the lack of clarity of an unrelated sentence in the PHB about long rests?

 

[iserith]

Can we return to the question about casters knowing saves instead of a threadjacking about the lack of clarity of an unrelated sentence in the PHB about long rests?

I thought the question was already answered - the rules don't really say, which of course didn't stop Jeremy "Shield Master" Crawford from weighing in with something completely unsupported by the rules.

 

[prabe]

As @iserith sez, there's not really an answer in the rules, either way, so you can rule however you want. The best advice has at least included the idea that you should be consistent. I personally think efficiency at the table and bad DM memory are reason enough to mark miniatures on a battlemat, but I see there being upsides to not being so upfront out of combat. Others--whom I respect--disagree. It might be worth talking over with the other people at your table, if you don't feel comfortable being unilateral about it.

 

[Lanefan]

I mean, sometimes it's blatantly obvious whether your spell worked or not - did your Hold Person target stop moving? If yes, it worked - but other times it's not, meaning that if the PCs want to know if the spell worked they have to do or try something further in order to find out. As in:

Player: "My charm resolves. Did it work?"
DM: <rolls a save; on any result says> "What are you doing in order to find out?"

Only on further investigation and-or intereaction with the target does the DM need to worry about narrating possible spell effects or lack thereof.

 

[Sword of Spirit]

As far as I can tell, there is no conflict between what Jeremy and the PHB says (that you only know what is obvious from the effects of the spell that are detectable with your senses or explicitly spelled out in the spell).

"Otherwise, you perceive that the spell did nothing to the target."

That's the tricky part. It seems to suggest that if you are dealing with a spell that doesn't allow a saving throw, you automatically know (perceive) that it doesn't work when you cast it on an invalid target. This turns those (admittedly rare) spells into valid/invalid target detectors. That seems to run contrary to the tone of the section, which otherwise presents it so that you don't get to use charm person as "detect non-humanoid".

It's possible that it's just less than clear phrasing and the intent was something like, "Otherwise, you do not notice any effect from the spell." Or even better, that last sentence could just have been left out entirely, since that concept should follow from the rest of the section.

I'm probably going to stick with the idea that spells that don't require concentration are fire and forget, and your only way of knowing if they work is by observing the effects (either physically, or with magic such as detect magic or identify). For a concentration spell, I assume you know when the spell is using your concentration, so you know on that basis.

 

[S'mon]

Since I'm rolling all saves in the open, in practice it's necessary to rule that both caster & target are fully aware - target knows they had to make a save, caster knows if save succeeded. I guess I might allow Deception vs Insight if someone tries to fake failing a save but the roll would still be visible....

 

[Li Shenron]

To add more fuel to the fire...

I don't think it's even necessary to say that since the rules are black & white (i.e. you either succeed or fail at a saving throws) therefore the world must be black & white as well. It can be so that the nature of magic in the world is in fact "a spell either succeeds on you or doesn't". But it also can be that the rule is merely a simplified model only for the sake of the game, and the nature of magic is non-binary, with a reality of degrees of effects. If this is the chosen approach, it would make even less sense to think in terms of whether the caster knows about a target's ST, the only thing that matters is the perceivable effects.

 

[Not a Hobbit]

I mean, sometimes it's blatantly obvious whether your spell worked or not - did your Hold Person target stop moving?

In the case of Hold Person (and others), it's even more blatantly obvious - Am I still concentrating on a spell?

 

[AnotherGuy]

Players are trying to break someone out of jail. They charm the guard into showing them where the prisoner is located and then to help letting him out.

Guard makes his save vs charm person - but thinks quickly.

Although cute idea, if you're going to be playing that close to the book and Crawford's rulings, the guard would also have to identify the Charm spell.

 

[Mort]

Although cute idea, if you're going to be playing that close to the book and Crawford's rulings, the guard would also have to identify the Charm spell.

The guard isn't reacting to the charm spell (which he would likely have no way to identify). The guard is reacting to the request that he help them break someone out of jail.