D&D 5E Using Sending to contact a creature who was disguised?

[MarkB]

So, just to throw out some extra wrinkles:

What if the person was disguised as a specific individual? Is there a chance that the spell would go to that person instead?

What if the caster has interacted with both the actual person and someone using a disguise to pretend to be that person? Who receives his Sending in that instance?

 

[BluejayJunior]

For the first one, I would probably have the spell fail. As was said above, I would just have the message sent and then no response, so it is vague whether or not it was received. Since they are not actually familiar with the real person or familiar enough with the person who was disguised. But I think the real person getting the message instead would also be a valid option.

For the second part, I would have the message go to the real person. Unless they for some reasons already suspected that there were two people and some of their interactions would were with an impostor. Then I would let them target which of the two personalities they want to send the message to.

 

[Coroc]

I would allow the spell to work normally. My reasoning is that familiarity is an ambiguous concept. How does one develop familiarity? Is it by knowing facts about that person such as their name and trivia about their lives? If so, a person could be familiar and cast sending on individuals they've never even met. But if this is the standard, then that same caster might be unable to successfully cast sending to contact the barista they see everyday that gets them their coffee and engages in small talk.

On the other hand, does familiarity come about based on interactions and shared history? If so, the foremost scholar on Strahd von Zarovich could not use sending to contact Strahd since they have never met. But they could use sending to contact their neighborhood, who they don't know terribly well but still get together during communal holidays.

So it really depends on how you define familiarity. Is it about concrete knowledge of that individual, or the shared experiences and interactions you've had with them, or something in between?

Personally, I lean in favor of interactions over concrete knowledge. Magic is ephemeral and about energy. I see interactions and relationships as being able to create invisible links of energy or impressions between others, and I see magic being better able to follow such links more easily than concrete facts and descriptions which can be obfuscated by perception and context.

Yes all your arguments hold true. But in this specific case, as far as OP wrote, They only did get a glance on that person while it was disguised. That is not covered by any of your assumptions, neither personal nor scholar knowledge is available.
Eventually OP elaborates some more e.g. did the party know the name?
I would allow the sending if the individual is in line of sight although disguised, although this is not specified in the rules, but this is about the only exemption I would make specifically in this case.

Familiar for me normally is in the context that you have more than some knowledge about something.
A wizards familiar is a companion creature which can be trusted somehow.
You are familiar with a city if you do not need a map to find some places, not if you only know the name of the city.
For persons only to know their faces and eventually saying hello once is not familiar in my point of few, so this alone already is a stretch.
Also having extended knowledge like your scholar with expertise on Strahd might not need anything else to make the spell work (Inside Barovia of course, not while in FR or elsewhere!)

 

[Ruin Explorer]

"Familiar" is vague on purpose.

Getting super-specific like having to know their face defeats the point of said vagueness and changes the spell into a different but similar spell. Which may be fine but should be carefully considered. I would avoid pinning this down, myself, because the spell does. Further, if you do get specific like "know their face" a giant can of worms opens with shapeshifters and the like. Indeed it could potentially instead become a shapeshifter detector if that road was taken. Which might lead to more house rules and when you have multiple sentences of house rules on a largely harmless low-level spell that didn't previously require any, you probably need to ask yourself some questions! I've been there!

If they'd spoken to the person in disguise many times, I'd definitely allow it. If they'd met someone briefly in an alley for a few sentences of angry back and forth, I probably wouldn't, disguise or no. I have some NPCs who habitually wear masks in my campaign and the PC are most certainly "familiar" with one of them.

 

[Blue]

As others have said, familiar is a vague concept. But it's a fairly low bar.

The Eberron changeling PC who has travelled with the group since it formed, and has many heart-to-heart talks but hasn't shown his "true" form - they are rarely seen in it. Are you familiar with the character? Absolutely. It doesn't matter that they are literal shapechanges who have never shown their true form.

It has nothing to do with divination or locating - it doesn't let you find the creature. It just "delivers the mail" to a familiar mind if it's on this or another plane. Specifically a mind. It's not looking for someone who matches the description. It's all mental so it can't "out" someone as well.

Personally, I'd rule you'd know if the spell failed vs. works with no response - it's detailed a few places and seems to be the 5e way. But that's my ruling with RAW being silent.

 

[Baldurs_Underdark]

Thanks everyone for the lively discussion! Lots of good input.

The scenario is one where the characters and disguised NPC actually exchanged words.

I am leaning to rule that the disguised NPC and players are familiar with each other, strengthened in that idea by those saying that the word familiar is deliberately vague, which gives me some freedom as DM. The storyline would benefit from a bit of communication. At least I feel now that such a ruling means I am within the rules and not bending them into something Homebrew. (Not that I have a fundamental problem with that, but I always like to know it when I do so).