Doppelganger detection


Strange Aeons


A doppelganger has copied a party member. Oh no! Dopps make a perfect copy, AND they have weapon and armor proficiencies, AND they get free Detect Thoughts at will, meaning they'll probably know the answer to any question you ask them before you ask it. Now what?

1) Dopps don't normally get spellcasting ability. So, if the party member is a caster, just ask it to spam a cantrip or two. (Note: dopps can take character levels, so one could in theory pass this test.)

2) Dopps have very limited skills, and they don't copy the skills of targets. If the party member is a skill monkey, ask them to pick a lock, tie a complex knot, do a backflip, or play the banjo. (Same caution as above, but if you meet a doppelganger who has character levels AND who has put ranks in the *exact same Perform skill* as your bard, it's probably time to give your DM some side eye.)

3) Detect Thoughts doesn't give you languages. Ask the dopp to say something in Elvish (or whatever your PC's backup language is).

Thoughts?

Doug M.


Detect thoughts has a save if you want to read minds. You know that you succeed a save.

PFSRD wrote:

Succeeding on a Saving Throw: A creature that successfully saves against a spell that has no obvious physical effects feels a hostile force or a tingle, but cannot deduce the exact nature of the attack.


Politely ask to strip all magical stuff and dispel all active spells on himself, then cast detect magic. Supernatural shapechanging abilities are detected by this spell.


gustavo iglesias wrote:
Detect thoughts has a save if you want to read minds. You know that you succeed a save.

Dopps can spam Detect Thoughts at will, all day long. So, sooner or later they'll get into your head.

Doug M.


Ashkar wrote:
Politely ask to strip all magical stuff and dispel all active spells on himself, then cast detect magic. Supernatural shapechanging abilities are detected by this spell.

Hm. Cite for this? "What can Detect Magic do" is an endless source of debate, but this is the first I've heard of it being able to pick up on a (Su) ability.

Doug M.


Douglas Muir 406 wrote:
gustavo iglesias wrote:
Detect thoughts has a save if you want to read minds. You know that you succeed a save.

Dopps can spam Detect Thoughts at will, all day long. So, sooner or later they'll get into your head.

Doug M.

Yes, but the relevant part was the second sentence. The first time they try, if I pass the save, I feel an hostile force or a tingle. I don't know if it's because of a detect thought or a charm person or what, but I KNOW that I have been the target of a spell or supernatural effect.

Dopplenganger's cover is not going to last long if he spams detect thought.


Sure, but since it's (Su), the dopp isn't obviously casting -- no verbal, no somatic. So, looking around for the caster gets you nowhere.

Also, if it's the classic "two versions of Bob -- which is real?" situation, then the tingling doesn't help. "Bob, what's your favorite color?" "It's -- hey, I just felt a weird tingle!" "No, *I* felt a weird tingle!"

It is potentially helpful if the dopp is trying to get the drop on an isolated party member. Rogue scouts ahead -> lurking dopp, who has taken 20 on Stealth, starts trying to read his mind -> DM rolls a good save behind the screen -> rogue feels a weird tingle. "I turn back and rejoin the party, fast!"

Doug M.


You know that the tingle is produced by a hostile force. As in, you know you have been the target of a spell or supernatural ability, and you succeeded the save.

In the example you give, with the scouting rogue, yes, the rogue would not know what targeted him. But in that case, if the rogue fails his save, the dopplenganger is not going to get a lot of info. He can read surface thoughts only, and rogues don't run around thinking about their favourite color.


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Douglas Muir 406 wrote:
Hm. Cite for this? "What can Detect Magic do" is an endless source of debate, but this is the first I've heard of it being able to pick up on a (Su) ability.

Here's the answer from James Jacobs.


The dopplegangers are really effective when they infiltrate somewhere and nobody expect them.

In a camp full of paranoid people searching for dopplengangers, not so much.

They are a great tool to make the players paranoid. A little tingle here and there, sometimes with Winter present, sometimes without it, can build up some tension.

Untilthe pcs cast detect magic, that,'s it.


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Ashkar wrote:
Douglas Muir 406 wrote:
Hm. Cite for this? "What can Detect Magic do" is an endless source of debate, but this is the first I've heard of it being able to pick up on a (Su) ability.
Here's the answer from James Jacobs.

Ugh.

I accept the answer as canon, or nearly so. (James Jacobs speaks with authority, but not final authority -- he could be overruled by an official FAQ answer.) But I think it's a really bad answer. Detect Magic is already painfully overpowered for a spammable cantrip; it can be used to detect the presence of invisible creatures, determine when someone is under an enchantment, and effectively detect illusions. Now it can be used to detect shapechangers too? That's just not balanced.

Note that this blows two of the encounters in _In Search of Sanity_ right out of the water.

In Search of Sanity:
There's an encounter early on where the PCs encounter an injured woman, pinned under some wreckage. The "victim" is of course a doppelganger trolling for prey. Judging from the PBPs, most parties aren't fooled, but the trap does usually trigger a lively discussion, with a minority of players either believing the woman or willing to give her the benefit of the doubt. Several parties have at least helped the woman out from under the rubble and talked to her before deciding what to do. It's an interesting encounter -- which is of course the point.

This rule interpretation kills that dead. The PCs now stand 30' away and cast Detect Magic. When they get a hit, they kill the doppelganger (which, let's note, is prone) with missile weapons. It turns an interesting encounter into a stupid one.

The boiler room encounter a bit later, same same. Half the interest there is trying to figure out which of the NPCs is the hidden dopp. One cantrip, and the PCs know which cup the pea is under, and can immediately focus all their fire. Again, this turns an interesting encounter with a lot of RP potential into a straightforward and rather pointless combat.

I have to say, _In Search of Sanity_ does not read as if the writer knew that hidden doppelgangers could be revealed by a simple cantrip.

Doug M.


My players don't cast spells at NPCs when they first meet them. If they tried I'd ask for initiative, as pointing to someone while chanting and surrounded by glowing energies is something most people would find hostile

Also, detect magic only tells you that there is a transmutation effect. You might be killing a dude with Ant Haul active.

Silver Crusade

Pathfinder Companion, Starfinder Adventure Path, Starfinder Roleplaying Game, Starfinder Society Subscriber; Pathfinder Roleplaying Game Superscriber

You have to concentrate for multiple rounds to pin down the exact type of magic and where it's at, so if you're trying to find a moving invisible target you're out of luck.

As for the spoiler

Spoiler:
The only Doppelganger that matched that description is one that transforms and drops if it hears people coming, pretending to be injured. It's not pinned under any wreckage or anything.

Ad if detect magic defeats the ruse then huzzah! It's not a major point of the adventure (really, it's just the opening of that adventure, not the entirety) and doesn't derail anything. No more than bringing someone with Trapfinding to a dungeon with traps.

Silver Crusade

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gustavo iglesias wrote:

My players don't cast spells at NPCs when they first meet them. If they tried I'd ask for initiative, as pointing to someone while chanting and surrounded by glowing energies is something most people would find hostile

Also, detect magic only tells you that there is a transmutation effect. You might be killing a dude with Ant Haul active.

Also this.

have the DG bluff, "I drank a lifting potion to try and move this but it's too heavy, help!"[/b]


Pathfinder Adventure Path, Companion, Lost Omens Subscriber; Pathfinder Battles Case Subscriber

My witch found a way to tell a doppleganger from a regular thing. She just uses her slumber hex, if it seems to not effect it in any fashion (such as being immune to sleep/mindeffects) it is a doppleganger. If it affects the creature (aka it makes a saving throw as it fights the sleep) then it isn't a doppleganger.


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That assumes that the doppleganger isn't impersonating an elf or half-elf -- then you are probably out of luck.

Of course, I am looking forward to my first chance to say to a doppleganger, "Oh, so you killed Fred and took his place? That's cool -- Fred was a real jerk, so we're glad we don't have to put up with him any more and that he's been replaced by someone who can actually be useful."


Pathfinder Adventure Path, Lost Omens, Rulebook, Starfinder Roleplaying Game, Starfinder Society Subscriber

Since Detect Thoughts is a spell-like ability, it will have manifestations whenever a doppelgänger uses it, no? If so, a doppelgänger won't have much luck using it while in sight of other PCs...


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Yes, he can't cast it secretly while observed. It's one of the WTF were they thinking implications of the manifestations FAQ for traditionally stealthy monsters like these rakshasha, and succubi.


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Plausible Pseudonym wrote:
Yes, he can't cast it secretly while observed. It's one of the WTF were they thinking implications of the manifestations FAQ for traditionally stealthy monsters like these rakshasha, and succubi.

Ugh. Just... ugh.

Not going to play by RAW on those, because this is a case where RAW makes the game less fun and interesting. Raks and succubi are supposed to be creepy, subtle opponents who can read your mind. As to doppelgangers, "you can detect them with an infinitely spammable 0 level cantrip" combined with "you can see when they're trying to read your mind" nerfs them into complete pointlessness.

I generally prefer to run things as close to RAW as possible -- a single unified ruleset just keeps things fair. But there are edge cases where, no, RAW just fails. In the particular case of this module, at least I can handwave "these are weird variant dopps created by interaction with the Dreamlands, so they may not follow RAW". But I won't be using dopps going forward.

Doug M.


Moving the detect thoughts to (Su) is a pretty minor thing that solve the greatest problem. Over ruling Jacob in the detect magic vs (su) is not a problem either, and it's a coin flip decision anyways, (Su) don't work in antimagic auras, but can't be dispelled. So pick which one you feel relevant.

Personally, I think the biggest issue might be stop allowing players to spam magic against NPCs. If your players want to detect magic in the dopplenganger at 30', roll initiative. Later, if they want to detect magic on Winter, or the Bard at the end of the adventure, or any other potential ally, roll initiative too. Detect magic is absurdly powerful for a cantrip, but exponentionally more powerful if the PC feel that magically invading the privacy of everybody they encounter is free of consequences.

I mean: will they frisk every NPC they meet, to search for hidden blades too?


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David knott 242 wrote:

That assumes that the doppleganger isn't impersonating an elf or half-elf -- then you are probably out of luck.

Of course, I am looking forward to my first chance to say to a doppleganger, "Oh, so you killed Fred and took his place? That's cool -- Fred was a real jerk, so we're glad we don't have to put up with him any more and that he's been replaced by someone who can actually be useful."

If they were an elf, she would still think they were a doppleganger. Didn't metagame anything. If it doesn't sleep, it's a doppleganger. Paranoia is her shtick.

We each started the game with one of the following:
Mania/Phobia
Multiple Personality Disorder
Paranoia
Psychosis
Schizophrenia


gustavo iglesias wrote:
Personally, I think the biggest issue might be stop allowing players to spam magic against NPCs... I mean: will they frisk every NPC they meet, to search for hidden blades too?

Gotta disagree. Throwing a DM is a harmless, non-intrusive way to check someone out. It may be rude, but -- unless the NPC is very paranoid or has a hair-trigger temper -- it's unlikely, by itself, to start a fight. "NPC's attitude immediately drops one level" would be a more appropriate default response IMO.

-- Also, I note that with Cunning Caster PF finally has a balanced, playable way of disguising spellcasting. Not everyone takes CC (the Deceptive feat tax is annoying and the high Bluff requirement is a limitation) but from what I see on the boards, it's become a reasonably popular feat for casters who are sneaky or social.

Doug M.


dt


Douglas Muir 406 wrote:
gustavo iglesias wrote:
Personally, I think the biggest issue might be stop allowing players to spam magic against NPCs... I mean: will they frisk every NPC they meet, to search for hidden blades too?

Gotta disagree. Throwing a DM is a harmless, non-intrusive way to check someone out. It may be rude, but -- unless the NPC is very paranoid or has a hair-trigger temper -- it's unlikely, by itself, to start a fight. "NPC's attitude immediately drops one level" would be a more appropriate default response IMO.

Casting divination spells on someone you don't know is not different than using electronic surveillance to read his smartphone, or use a metal detector to check for weapons. It is really rude. It is something you accept (and unhappy) wheb it is done by the authority, for safety reasons, not something you allow to every person you just meet. Also, DM is only harmless if the target has spellcraft (and pass the check). For everybody else, there's no difference between gesturing to cast DM, and gesturing to cast Finger of Death.

The fact that you roll initiative doesn't necessarily imply a fight. Certainly the NPC could be a wounded lady, and depends on her motivations, could drop one level in attitude, run scared, or be indifferent. But it could be a doppleganger, and them he has the right to act in the same round you are casting Detect Magic. He could be also a short tempered superstitious barbarian, who is CG and a possible ally, but reacts badly to magic. Who knows. Thing is, if you want to cast a spell, which is something obvious unless you have feats to conceal it, the rest of the world doesn't freeze until you stop chanting. As soon as you (declare to) start chanting, everybody has the right to act. Same than if your PC instead of "I cast Detect Magic at 30'" says "I cast Snowball at 30'". The dopplenganger would roll initiative for the second one. And has no way to know if the first one is a different spell


If the person is acting suspicious, then they deserve being checked out. That has nothing to do with whether they are a doppelganger. Charms, possession, illusion, et cetera are valid concerns.

Doppelgangers aren't stupid. If it is arousing suspicion, it will split. So it won't copy someone it can't effectively mimic except for a brief tactical advantage. Also, it will probably try to create a distraction by focusing folk's attention on some reasonable other crisis.

Nethys says it is unreasonable not to be casting magic spells all the time. Don't stop players from using the tools they've got. But identifying a spell effect in place is Knowledge-arcana check DC 20 + spell level. Add a circumstance modifier, so DC 24, rolled by the GM, if suspicion is aroused.


I don't stop them. They can cast their magic normally, in their initiative count.

In fact, the NPC can, and will, cast their own magic in their own initiative count, too, pleasing Nethys twice as much.


Petulengro’s Validation: A handy spell for dealing with Doppelgangers...


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Well, fire always works!

(Is 35 years long enough for spoilers?)

Liberty's Edge

My party has a paladin so whenever a dg comes by the paladin checks the players for evil. He also checks dead bodies just in case

Silver Crusade

Pathfinder Companion, Starfinder Adventure Path, Starfinder Roleplaying Game, Starfinder Society Subscriber; Pathfinder Roleplaying Game Superscriber

That wouldn't really work that early though, aside from Evil Aura class features or Outsiders or Undead you don't give off an Evil aura until 5th level/HD.


Okay, here is a cheap, no magic, no stress, no chance of accidental murder to your party way to detect a doppleganger 100%. This will also work on other natural shapeshifters.

First question both party members until they insist they are the real one.

Then separate them, ask them to give you a lock of their hair. You can easily shave a bit of hair with a simple dagger. Take the hair locks and hold them in separate hands.

Then wait.

Your real party member's hair will stay a lock of hair. The doppleganger's hair sample once separated from the body will not be able to maintain the shapeshift, it will revert back to... Doppleganger goo.

I imagine this is how the local peasant community catches a doppleganger in their midst, no fancy magics necessary.


That's more or less the method used in "The Thing". Not clear if it would work on a creature using Alter Self, though.

Doug M.

Silver Crusade

Pathfinder Companion, Starfinder Adventure Path, Starfinder Roleplaying Game, Starfinder Society Subscriber; Pathfinder Roleplaying Game Superscriber
Dr. Guns-For-Hands wrote:

Okay, here is a cheap, no magic, no stress, no chance of accidental murder to your party way to detect a doppleganger 100%. This will also work on other natural shapeshifters.

First question both party members until they insist they are the real one.

Then separate them, ask them to give you a lock of their hair. You can easily shave a bit of hair with a simple dagger. Take the hair locks and hold them in separate hands.

Then wait.

Your real party member's hair will stay a lock of hair. The doppleganger's hair sample once separated from the body will not be able to maintain the shapeshift, it will revert back to... Doppleganger goo.

I imagine this is how the local peasant community catches a doppleganger in their midst, no fancy magics necessary.

I know they revert on death but I don't know if cutting the hair would it make it revert, though it's highly likely.

That being said if you're just gonna do that why is all the questioning needed up front?


Pathfinder Adventure Path, Lost Omens Subscriber

I've houseruled that detect magic does not reveal the magical aura of creatures' supernatural abilities, although higher-level magical detection spells (i.e. identitfy, analyze dweomer) will.


Once s#*! hit the fan and the infiltrated doppelganger attacked the party, they accidentally discovered a way to find one. "Daze" doesn't work on Monstrous Humanoids, as the wizard discovered when tried to daze the doppleganger.

So then they proceed to roll bluff, diplomacy and intimidate, and use their reputation within the group (they did all tasks, such as cooking, healing the wounded, etc). Every NPC agreed to pass the exam, and being Dazed (although some of those NPC had to be coerced).

The PC were surprised when Winter did not get dazed and almost tried to kill her (I changed the Changeling type to Monstrous Humanoids too, just for the giggles)

BTW, I made Winter to be a Changeling from Grizmelda, in the town. Also made her to receive the Changeling calling from Thrushmoor's Coven of Hags (which I made more relevant to the story)

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