In my homebrew world, doppelgangers have their society. Because they could imitate anyone, each doppelganger wears a personalized mask at all times. The higher quality the mask, the more influential and powerful the doppelganger is. 

Quote from Thauraeln_The_Bold >>

In my homebrew world, doppelgangers have their society. Because they could imitate anyone, each doppelganger wears a personalized mask at all times. The higher quality the mask, the more influential and powerful the doppelganger is. 

That's interesting. I have some ideas on what doppelgangers are like in my world, but I've barely started.

Feels like me

Anyone having fun playing on in Rime of the Frostmadien?

Quote from Thauraeln_The_Bold >>

In my homebrew world, doppelgangers have their society. Because they could imitate anyone, each doppelganger wears a personalized mask at all times. The higher quality the mask, the more influential and powerful the doppelganger is. 

 This is a good concept.

Even in a setting where Dopplegangers aren’t so open, they might still process such a mask to verify their identity (like a noble’s signet ring) with others of their kind.

Quote from SethTheFrank >>

Ok, but what do they actually want? Just money and ease? Ok, as I write this, that sounds pretty awesome. But it seems like they could get that. And then what?

 This seems like an awesome life

I think Doppelgängers should be any alignment; neutral seems like a waste of possible character development and story arc

Quote from DrWylieAlexios >>

I like the notion that they are guided by their true neutral alignment. As an example, in the Lost Mine of Phandelver beginner box adventure, they are working for the drow, posing as drow. Yet, when given the opportunity to acquire the map to said mine and captivity of the dwarven owner, they would destroy the map and kill dwarf, preferring to keep knowledge of the mine kept from both sides: the evil drow and the good dwarves/PCs.

 Spoiler! 

whatever self-interest they have ,they can accomplish with money and power

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I don't understand the ambusher trait. I mean, I get what it does mechanically, but isn't that true for any NPC or PC?

 

Normally, attacking a surprised creature does not grant advantage. The ambusher trait is an exception to this.

https://www.dndbeyond.com/sources/phb/combat#Surprise

 This changes everything.

 

Unseen attackers are what get advantage on Attack rolls (specifically, “an attack from hiding”).

A Doppelgänger’s surprises tend to be more of a “sudden betrayal” then a “sneaking up” situation.

 Curse their sudden but inevitable betrays? ;)

As doppelgangers and Changelings are so similar, but Changelings are a playable race. I've been toying with having Doppelgangers only being able to change into a creature they've recently killed. and the blood of the slain gives it that creatures most recent memories (30 days).

*Homebrew world thoughts incoming*

As dopplegangers and changlings are very similar mechanically I've started developing some thoughts on the shapechanger genus with them being subspecies along with mimics and maybe others. Keep in mind this is a very rough draft thought. 

The main separation being the way their abilities manifest:
-Dopplegangers can only do living things, humanoids specifically, and only full body transformations.
-Changlings can do full body transformations, but it's harder for them and they can't maintain it as long as dopplegangers. They in turn have more freedom of expression with their changes and the ability to do smaller aesthetic changes like hair, eye, and skin color individually.
-Mimics specialize in more bait type transformations than deception tactics. They are the only ones who can do inanimate objects, and while they can do humanoids and animals their forms are imperfect. Always something slightly off about them. They also can do small changes that are more physical like changing a limb into a mouth or similar.

They each would vary dramatically mentally as well:
-Dopplegangers as a race tend towards hedonism and socipathy. They tend not to have consciences or care about consequences. Though there are very rare exceptions.
-Changelings are the most pliable mentally. They are most like humans in they can be sweet, cruel, empathetic, socipathic. The variety is endless, though they tend towards the artistic.
-Mimics while they have the strongest shapeshifting abilities and flexibility to their physical forms, they are usually feral and animalistic in mindset in general. Sentience is uncommon, not unheard of but you're not likely to find a mimic city. Those that are sentient tend to be isolationist and keep their interactions with humanoids to a minimum in most cases as prolonged contact leads to uncomfortable questions when intuition picks up on the inconsistencies with their form.

No idea if anyone will read this, but is there a certain contest for the action 'Read Thoughts' ? Like the doppelganger's Charisma check vs the victim's Wisdom save ? 

from my understanding a lot of them cycle through rich people to impersonate. Like, yes, money and ease and some amount of hedonism. Like, replace a rich person, live high and spend all their money, then move along to another is the ideal cycle. Most however can't do that easily so that's why you get them working as spies and stuff to make ends meet. Idk, that's just my take on it. As far as heart's desires go, that'd vary a lot from doppelganger to doppelganger.

Here are a couple of fun changes if you are looking to make an improved version of them.

Let it eat brains (to gain the knowledge and characteristics of the creature it has eaten), let it cast Disguise Self at will (to change the appearance of its clothes namely), and let it use its Shapechanger feature as a bonus action. This allows this creature to be so much more interesting because you can have it regularly shift and use that against the party.

Quote from SethTheFrank >>

Ok, but what do they actually want? Just money and ease? Ok, as I write this, that sounds pretty awesome. But it seems like they could get that. And then what?

 It seems to me that these are meant to be a versatile monster easily used in any situation. They could be with a small group of bandits for loot or they could be masterminding a rebellion. If you are asking as a player, your DM may put these in any number of situations. If you are asking as a DM, it’s up to you. Since their alignment is true neutral, they would likely be doing whatever it is they choose to do for some from of reward, not for morals. Keep in mind though that you can change their alignment based on what you need them for.

Doppelgangers work alone or in small groups, with group roles shifting from con to con. While one doppelganger takes the place of a murdered merchant or noble, the others take on a number of identities as circumstances warrant…

Especially because of this and taking it a step further, I have found that they are terribly effective when they use non-doppelganger accomplices, too. By maintaining a couple different characters/identites, they can easily pit sides against one another to sow chaos to buy them time when they need it for one character/identity, meanwhile keeping the other characters/identities stable.

Who needs friends when you can be your own, and use their friends in a pinch. Build up enough credit with one or two identities and you’ve got big leverage. The key is that the different identities don’t ever need to be in the same room, and that their “alliance” is either fitting expected, stereotypical tendencies or infrequent.

An elder doppelganger is likely to understand the norms and cultural stereotypes of a whole network of interrelated sub-cultures as a matter of how it survives. And a role as a famous actor with an adoring, infatuated fanbase is a perfect cover for it.

Recommendation: have these doppelgängers work alongside a fractine, if possible.

The fractine would allow the captured target to be held indefinitely, without fear of starving to death (as a target held in stasis by a fractine does not require food or water).

This also allows a doppelgänger to assume their identity for prolonged periods.

A dastardly pairing!

Imagine doppelganger being a playable race and framing people for murders and stuff.

I modified the doppelgänger to my homebrew campaign to want to eat children just because children, idk if there’s an official thing