Doppelganger, who has used them?

[SMac8988]

So I have a idea in my next session for my players to have one of their own, unknowingly, replaced by a doppleganger.

The idea is that they will walk into a temple area that will be a prison for the doppleganger. When they enter their will be a sleep spell barrier, that will knock then out. The lowest save will be replaced by the doppleganger and their body hidden away.

The group can find them, but is unlikely with high investigation checks.

The idea is the doppleganger will pretend to be that player, and I'll have the player continue to play their character unknowing what all happened. From there they will continue throguh the area they are in and unless they are really suspicious I doubt they would think to check into it.

When they get into a fight, the person taken over will be unable to cast spells or use any magicy abilities or attuned items. At that point they will be confused and start looking into it.

My idea would be that the person they replaced would wake up once the doppleganger is caught and would have to catch up.

Is this how you play them properly?

[Corran]

For simplicity's sake, I would say let the player play his character as normal (so let them use their abilities normaly), but make sure to give a description of this player's actions that slighlty differs to what the player says that his character is doing (emphasis on slightly, as it is nice to drop hints and not just straight point out that something is off). This way the player gets to keep playing their character as intended and they are having fun, and you will still puzzle your more insightful players without delaying play because if questions ''why can't I do this?''. All this can be justified if you consider the doppelganger being a class very similar to the class of the character it substituted (and that's the reason the doppelganger substituted that character). So for example if the player whose character is subed is playing a wizard, then the doppelganger has levels in some arcane caster class and is thus replicating the wizard's spellcasting with its own spellcasting (your description will not exactly match what your player is doing 100%, so that will provide the hints, but mechanically play it like as if the player was palying his own character to speed things up).

As for when the group will bump into the original character, well, that is for you to decide. If it was me, I would have this go on for quite some time, and then after some considerable time had passed, I would have the original character (played by me as an NPC) confront his imposter who up to that point is travelling with the group. Makes for a good hold-the-door/Hodor -esque moment.

[MrStabby]

I have never played a doppleganger so treat what I say as thoughts, rather than direct experience.

1) What does the doppleganger want? To get out? To kill? To release other family/friends? What is its character and why was it imprisoned? The player who plays the doppelganger should be given a list of objectives.

2) What does the doppleganger know? How is what it knows different from what the player would know?

3) In an ideal situation you want the characters to wake up and only begin to suspect anything by an oddity in behaviour. The problem is you are giving them a lot of metagame knowledge which will be difficult for the players to ignore. You asked for a save, they probably observe someone roll badly, but don't know what the repercussions are. On the other hand the players still see the player playing their character - even if they get suspicious this will be a big hint that there isn't a doppleganger.

Personally I would have the party find the doppleganger's cell empty and enough documentation for the PCs to know a doppleganger is in the area. If they are on the lookout it becomes "fair". I mean this in the fun sense - they are engaged with a game of working out who the doppleganger is, maybe they just think it is an NPC, maybe in the party. Presenting the players with a game or challenge that they are not actually partaking of means that they are not getting the benefits.

[spartan_ah]

I used a Doppelganger as a spy for a counter kingdom that convinced the party to be their guide.
he helped them infiltrate a castle in order to make the king's army to lose the battle. they suspected him once in a while, but their insight rolls were poor comparing to his deception. he even posed as one of them to commit a murder and have them take the blame. he did a good job, only one time he tried to sneak out and one member insisted following him... to my luck he rolled 1 on stealth and had to retreat...

[Baptor]

In my last campaign I had a traveling priest team up with the party for awhile who was a doppelganger.

Not long after meeting him one of them said, "with our luck he's probably a doppelganger." I was petrified at first but they all laughed off as a joke.

Needless to say that player was delivering a lot of "told ya so's" after they found out!

[Grod_The_Giant]

The idea is the doppleganger will pretend to be that player, and I'll have the player continue to play their character unknowing what all happened. From there they will continue throguh the area they are in and unless they are really suspicious I doubt they would think to check into it.
That's brilliant and evil.

[SMac8988]

That's brilliant and evil.

My idea is exactly that. To let it go as long as possible without me getting involved.

His goal is to get out if the prison temple he was stuck in. So as the enter the temple, it's defense is to knock out intruders so he took he was most out.

I considered letting them play at full ability but some of my players may not catch on, like forever. And at that point they may just accept the doppleganger into the party and accept the other guy is lost forver.

I like the idea of evidence about the ganger, idk what all to leave though, maybe just evidence something was there and like old skins of something of it just transforming to practice? Give them hints but not tell them exactly what it was.

[Mellack]

The Doppleganger shouldn't really be able to fit in with the party. The MM specifies that it does not gain languages, mannerisms, memory. or personality. It is supposed to follow and study people to gain those. Since you want it to replace someone right at the beginning, it wouldn't know any of the other party members or how it should treat them. It especially wouldn't know mannerisms like the person's accent or habits.

[MrStabby]

I like the idea of evidence about the ganger, idk what all to leave though, maybe just evidence something was there and like old skins of something of it just transforming to practice? Give them hints but not tell them exactly what it was.

Journals of the guards. Have a few left behind, each giving a different description of the prisoner. Maybe a weapon more effective vs shapeshifters or a magic item that lets people see different forms?

[SMac8988]

The Doppleganger shouldn't really be able to fit in with the party. The MM specifies that it does not gain languages, mannerisms, memory. or personality. It is supposed to follow and study people to gain those. Since you want it to replace someone right at the beginning, it wouldn't know any of the other party members or how it should treat them.

I am gonna alter that for my game that as long as the person is unconcious and alive it maintains a psych link to maintain their memories and all. Via super natural. Which I'll also allow the player to roll a save to see if they wake up, or whatever to cause the ganger replacement to start to fade.

I just feel it adds more that they can copy memories, I also may try and gave him get away and be a returning character, like pop up later and try and get the groups help and become a psudo allie

[SMac8988]

Journals of the guards. Have a few left behind, each giving a different description of the prisoner. Maybe a weapon more effective vs shapeshifters or a magic item that lets people see different forms?

Weapon idea is cool, cept they may just cut one another straight up to see who all gets effected more or something.

[Hrugner]

I tried something similar, but the party allied with the group of doppelgangers(thinking they were other adventurers) and the faux-PC had to stay undercover not to break the truce. So I don't think they ever knew what happened to be honest.

[AmayaElls]

Personally, and I guess this will depend on your players, I would say let the person playing the doppleganger know. When they get knocked out take each person aside to talk about the "Dream" they had when hit by the spell. The worse the save he more nightmarish or something like that. However at that point let the player of the doppleganger know they have been replaced, a good player can then drop their own subtle hints to lead the party in roughly the right direction. If you make it clear to the player roughly how long you want the charade to go on for they can hopefully do play it pretty well.

However this does depend on the group, my group is very much into the communal storytelling aspect of D&D and any of us would just have a blast with this and I think do it pretty well. Your mileage may vary.

[SMac8988]

Personally, and I guess this will depend on your players, I would say let the person playing the doppleganger know. When they get knocked out take each person aside to talk about the "Dream" they had when hit by the spell. The worse the save he more nightmarish or something like that. However at that point let the player of the doppleganger know they have been replaced, a good player can then drop their own subtle hints to lead the party in roughly the right direction. If you make it clear to the player roughly how long you want the charade to go on for they can hopefully do play it pretty well.

However this does depend on the group, my group is very much into the communal storytelling aspect of D&D and any of us would just have a blast with this and I think do it pretty well. Your mileage may vary.

This would work if I was in person with this group. But sadly it's online and a few of my players are brand new to d&d and don't want to make them have to work on that level of story involvement just yet.

[Gignere]

Used them based on one of the random encounters from HotDQ I had so much fun with them I made them into a 3 session, mini story arc. In the end the doppelgängers survived, and even lived to come back and screw with the PCs again. Anyway the two CR 2 creatures basically framed the party for stealing and looting their own members, it was glorious.

Honestly if you use the doppelgängers in a devious way and can some how split the group after the doppelgängers have spent some time learning about the PCs you can wreck havoc on even a supposedly easy encounter for the party given their levels.

Long story short the two doppelgängers pretty much looted the party and caused half of them to be arrested by authorities and they nearly came to blows believing the other party members have wronged them. It was too awesome.

[Tallis]

technically not a doppleganger but I did have a shapeshifter replace one of the PCs in a superhero game I ran. I told the player what happened and let him play it. He did drop hints for the other players that something wasn't right but that just added to the fun. All in all it turned out great and and everyone had fun.

[Arkhios]

I don't think there's only one proper way to use a doppelganger. Being as versatile as they are as shapeshifters, two doppelgangers could play very differently from one another.

Anyway. I recently used a doppelganger as an assassin, hired by a Bad Guy to, successfully, assassinate a Nobleman, and consequently the Bad Guy had my players framed for that assassination.
Then, as the "fact" that the players were the culprits went viral, and officials put a price on their heads, this same doppelganger pretended to be one of their trusted allies (who he had previously killed and taken his identity) and gave them reasonable advice and direction to look for help. My players trusted their ally because they had no reason not to.

Long story short, the doppelganger led the group into a trap and assaulted them, to cash in the price for their heads, and to falsibly free his employer from any connections to the murder.

I had underestimated my group (two rogues (assassin and Arcane trickster) and a death cleric) and they made swift work with the doppelganger, while I had assumed it would've been longer fight. Then again, I think it fits perfectly for both the Bad Guy and the doppelganger to be arrogant enough and believe the adventurer's as easily disposable pawns in their grander schemes.

I'm eager to see how the story unfolds, as I'm writing it up as we go forward. As of now, they have a hint of the Bad Guy's intentions and a, obviously, fake name for him.