I suggested to my GM a campaign idea where one of the player characters would secretly be the final enemy boss and the player would play and campaign alongside the group trying to further his goals using the party as means to his ends. Eventually the party would find out and finish him off (or be killed off by the villain after a while).

My GM thought it was a very interesting idea. We plan to keep the premise secret to avoid metagaming, but have discussed this in a general sense and are confident players won't be put off by this kind of campaign concept.

We have never played such a campaign before though, and the primary problem seems to be not having the conflict come to a head too early, for the villain PC to simply kill everyone in their sleep, etc. We want the campaign to go a while before the conflict comes, and also want it to end with - even if not a straight up tactical fight, at least something that will be a interesting conflict.

What kinds of things should we take into account for both forcing the timing of and balancing the inevitable final battle?

Things like forcing a moral compass to prevent underhanded bad guy wins by killing everyone in their sleep. Would a level buff to the villain to the equivalent of matching the CR the party would face be useful? At what level would be a good point to tell the bad guy he can should try dropping hints, if the party figures it out early and moves to take him out then he’d be at a disadvantage.

If you've run a campaign like this before, how did you arrange it to solve this problem?

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    \$\begingroup\$ Also, you are welcome to read Good Subjective, Bad Subjective which explains very simply how we handle subjective questions on SE. It has to do with asking for specific things from experience and not asking for speculation and opinion. \$\endgroup\$
    – mxyzplk
    Commented Apr 7, 2017 at 12:51

5 Answers 5


First, probably the best way to prevent the party from betraying each other too early is to make sure they need each other alive, up to some point, and they know it. At the very least, the villain player should need the other players alive.

For example: The goal of the campaign is to open the Demon Door and defeat the Demon King before he returns to his full power and fills the world with evil, but the door can only be opened by 4 (or however many people you have in your party) legendary heroes. That way, they can't kill each other before the end of the campaign.

Now, when they fight, you probably want them to be on roughly even ground. I'm going off my D&D 3.5 knowledge here, so it might not quite apply to 5e, but if an encounter is equal to the party in power, it has a CR of 4 higher than the party's level. This assumes a party size of 4. So that could be one character of 4 levels higher than the party, or 4 characters the same level as the party (e.g. literally the same as the party), or your villain and 3 monsters.

For example, when they get past the demon door, the villain is possessed by the Demon King and gains his power (instantly gaining 4 levels; have him make a separate character sheet before hand). This is still in the rest of the party's favor unless there are only 3 of them now, action economy and all. Or, give him control of 3 demons with a CR equal to his level.

So that would be an equal encounter ROUGHLY, as a rule the side with more people at the same CR has an advantage. Now lastly how can we play with the intrigue a bit more? You could have it so that the villain has an advantage if they get to the fight against him without knowing who the villain is, but the party has an advantage if they figure it out ahead of time.

For example, when the party realizes someone will betray them, they can seek out an artifact that will stop the villain from being able to gain his levels or demon allies when they reach the demon king. But, they have to know who the villain is- if they use it on the wrong person, the villain still gets his demon king powers. But if they've guessed who the villain is correctly, they'll have a huge advantage in the final fight. If you're doing this, you might want to make it so that the villain can (for example) gain 5 levels instead of 4, or have 4 demon allies instead of 3 when the party has failed to guess who he is, so he really has an advantage in the fight.

In summary:
How I'd do it is make it so the party all needs each other to enter the final dungeon and can't kill each other ahead of time, the villain gets powered-up to boss-enemy level when they get to the final room of the final dungeon, and the party can stop that from happening but they have to guess who the villain is correctly.

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    \$\begingroup\$ Have you done this before? What is your experience with actually doing what you suggest? \$\endgroup\$
    – nvoigt
    Commented Apr 19, 2017 at 17:04

Don't do it.

I have been a player in an evil campaign where some of the PCs were directly antagonistic to one another. While some of it was quite fun, the player antagonism was decidedly not. There are a few reasons for this:

  1. PCs are not balanced for PVP. A 1v1 fight might be a toss-up, but a party fighting against a single PC-classed enemy will almost always win. In games that I've run, my players have mopped the floor with PC-classed enemies more than twice their level, simply because the action economy is so important to 5e.

  2. I don't think that betrayal and secrets are fun in D&D. Even though the whole party (including me) had bought into the premise and expected betrayals to happen, the moment of betrayal still sucked. When the party wizard suddenly turned against me and got me killed, I still felt kind of unhappy, even though I knew it would happen eventually. This should give you pause when trying to determine if your players really want this to happen.

  3. We found the logic to be difficult to pull off. As you point out, it's going to be difficult to create an "interesting conflict" that's not terribly one-sided. If the "good" players suspect that there might be a mole in the party, they will either hold the dissonance in their minds and play their characters into a betrayal anyway, they will gang up on the antagonist when they have an advantage, or they will simply be surprised out of nowhere. Consider facing a twist like this in a video game: if you've worked out that your ally is secretly evil but are forced to pretend like you don't know, it's very easy to feel frustrated. Ultimately, one side or the other is going to hold a pretty lopsided advantage.

If you really want to do this...

If you still want to try this, there are a few things to consider.

  1. The antagonist and the players are controlled by an external force. In our evil campaign, the only things keeping us from each other's throats was the fact that an omnipotent wizard was using us as playthings. This functionally boils down to GM fiat and deus ex machina, but it worked for the kind of zany campaign we were playing. You could introduce a plot point like this to keep everyone cooperating for a while.

  2. The antagonist needs significant support. As mentioned above, a single PC will almost definitely lose to the rest of their party in a straight fight because of the action economy. The easiest way to give more actions is to give minions of some kind, instead of giving the antagonist a power boost. You could consider things like ambushes, but my personal experience with such things tells me a sudden, lopsided fight at the end of the adventuring day is more annoying than interesting.

  3. Telegraph the betrayal well in advance, and make sure your players get the message. In my campaign, one player told us, "I'm going to kill you all one day". You need to likewise ensure that your PCs know that a betrayal might be coming. For example, you could have the antagonist PC escape with another villain at the end of a fight, and then return for the final conflict. Essentially, you need to ensure that your players won't be shocked by the twist ending, even if it means you have be super obvious about it. Of course, this feeds into point 3 from above--you're going to be walking a very thin tightrope for the whole campaign.

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    \$\begingroup\$ I'm not sure that telegraphing the betrayal is necessary; the villain need not be there for the express purpose of destroying the PC's and all they hold dear. He might not even be evil, but have a purpose that is hidden from the rest of the party. The antagonist PC might be manipulating the party for his own ends, whether world domination or just revenge on the King. That last would be excellent for the villain to be working toward; the PC aren't his target, and he has significant reason to be after the King. If the PCs suspect that they're being manipulated, they can act on it. But if not... \$\endgroup\$
    – Chemus
    Commented Apr 7, 2017 at 18:17
  • \$\begingroup\$ I agree with point 1 but the second and third are opinion-based. It all depends on the table and how the interactions and build up happen. Some players like intrigue more than hack and slash and betrayal is definitely part of that even intra-party type. \$\endgroup\$
    – Slagmoth
    Commented Apr 7, 2017 at 18:42
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    \$\begingroup\$ @Slagmoth, they are opinion based, but they also describe my personal experiences with this issue in such a campaign. \$\endgroup\$
    – Icyfire
    Commented Apr 7, 2017 at 18:45
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    \$\begingroup\$ @Chemus, while I think that's a good point in general, the end goal of the asker's campaign is a conflict between the PCs and the traitor. Having that plot point, which is both the climax and the ending, appear out of nowhere is probably not a good idea. \$\endgroup\$
    – Icyfire
    Commented Apr 7, 2017 at 21:04
  • \$\begingroup\$ Building a monster with the PC's class features, appropriate HP for a monster of the CR you want, and legendary actions/resistances is probably better than using a PC directly. \$\endgroup\$
    – r256
    Commented Apr 10, 2017 at 13:55

I played a quite long L5R campaign where one of the players finally became the final boss, and it was really intense, so I won't be on the "don't do that" side of the force. However this campaign wasn't planned to end like this from the beginning: it was more a series of unfortunate events that made this PC turn more and more corrupted, until he finally became a real monster. I'm not sure you will get the same effect by deciding from the beginning he is a traitor but it may be worth trying.

About the balance aspect

L5R doesn't work at all like D&D but I guess what my GM did works pretty well: just take a monster your party is supposed to be able to fight at this level. When the time came our GM just gave the player the mob's sheet. I can't really help you on how to choose the best CR, but don't forget to take into account that the team will have one less member for this fight.

About the story aspect

A common problem with playing traitors is that it's usually too easy not to be caught. In real life when someone is lying to you day after day you can end up with figuring things out. If at some point he is behaving strangely you will try to find why. In a rpg most of the time you can assume it is because the player is getting sleepy and have difficulties to keep his roleplay consistent, and you are usually encouraged to assume your teammates are not traitors to help the GM make an interesting story. That means for this to work the other players should have other hints, and usually small subtle hints are not enough.

I think what made this great in our campaign was that we all already knew it will end like that, but still couldn't get rid of him before the end. His corruption made him so powerful we needed him to win the previous battles. I highly recommend building a progression in how obvious it is that it will end that way, while adding new reasons why the group shouldn't just kill him right now without waiting for him to become the final boss.

Maybe he knows about the weakness of another big villain or is the only one who can defeat it in the prophecy... so basically he can help them go through the final dungeon, deal the final blow to Devastator the Bad, and only then absorb Devastator's strength and turn against them.

Or maybe the bad guy is sealed inside a nice one and the PCs, as they are good guys, can't punish an innocent. During the fight with Devastator the nice guy is almost killed, call upon the power of the sealed to survive, and Bigger Bad ensues.

What is important is that the PCs have a good reason to keep your guy in the team, because if they don't you won't be able to betray them in the end. But it is also important that they know this is a risky move so they will be able to accept the result.

You can add similar reasons for the traitor not to betray sooner (here are some examples):

  • maybe he needs the rest of the team to steal the lifeforce of Devastator (basically he is using them)

  • maybe he needs to grow in power before betraying them and the safest place for this is among the other PCs

You can even have some moral limitations that will disappear later, as you turn more and more evil, the possibilities are endless!


I tried this a few times, with varying degrees of success. While it SOUNDS cool, usually it will lead to resentment among the players. Not just from those who are getting betrayed, but some other players who were not chosen as the villain.

  • Keep it short nothing worse than have a campaign where you invested months/years turn out to be a big betrayal plot by someone you thought was a friend. This also has the advantage of preventing chances of spoiling the surprise. I once had a DM get punched in the face when after a good 6 months campaign, the party and the world got dispelled, everyone was a illusion. Don't do that.

  • Have everyone in on it Here I mean: everyone is out to betray the party, but secretly. A clear goal and a good signal is essential here "once you've opened the gate to the Demon King" (to use the above example). Since everyone is secretly in on it, this will be memorable. This is basically how I ran my vampire campaigns.

Good luck.


I wanted to add the twist I gathered from the board game Betrayal at House on the Hill, in case others want more ideas:

Tell no one what will happen.

Not even you know which Player Character will turn on the party. Play as if there is a different end boss and after this boss is defeated they reveal they were only trying to contain the true threat.

You then roll to see who will be the real boss. You will need to alter stats and likely add skills depending on who ends up as the boss. Might be worth ending for the night on the cliff hanger. Then inform the betraying party and let them familiarize themself with any character changes.

Then up to you. End with party or boss dying. Or end with party defeating the player boss only to save him from whatever spirit was possessing him.

You can actually pull a few ideas from that board games manual if you do like the concept. My players love a good twist. Winning isn't as important as the story imo.

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    \$\begingroup\$ Hi, welcome to the site—no worries about reviving a “long dead” question, questions don’t really die around here. On the other hand, we do prefer answers to be a little more than just “oh hey here’s an idea I had”—it’s important to back answers up. Your experience with Betrayal at House on the Hill is relevant and counts, so I think this answer is valid, but to be a really great answer it would be better if you had done it in D&D, or could point to someone who had. So if you ever try this, be sure to come back and edit in how it went! \$\endgroup\$
    – KRyan
    Commented Dec 24, 2019 at 20:43
  • \$\begingroup\$ Unfortunately, I don't think suddenly telling a player without any forewarning they are the final boss would be very fun. Playing the secret bad guy would definitely need be something the player is willing to play ahead of time to be enjoyable. \$\endgroup\$
    – Clarus_Nox
    Commented Dec 25, 2019 at 23:24

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