Hey, all! 

I'm a newer DM (Just under a year of experience) running a homebrew campaign for the first time. That doesn't have much to do with what I'm about to ask, but I figure if it opens up any new solutions it's worth bringing up. Having a lot of success with the module I had just wrapped up, I decided to invite one of my friends from a more combat-focused campaign to play a homebrew monstrosity of my own making. They had a quite Combat-focused min-maxed character in that previous campaign, but I didn't think much of it at the time since that more or less just matched the tone of the module. During session 0, I made it clear that this campaign was mostly mystery and RP focused, so players should build their characters around RP and narrative concepts they found interesting. I also told them that they should try to build their characters on the mechanical side with the rest of the table in mind (I was envisioning a 5 of the same class situation, but it also served as a warning to keep other players in mind with any one character's power level). Around a few days before the first proper session, I received my friend's character sheet. He had built a rogue with 60 ft. of movement that could sneak attack every turn and did what I calculated to be an average of 40 damage every turn (this was a level 5 campaign, by the way). I wasn't really sure what to do with that, but figured that since combat was falling to the wayside this campaign I shouldn't worry about it much, so I messaged him asking a few details about spell choices, backstory, etc. so I could incorporate that into the first session and the overall campaign. That's when he told me that he didn't actually come up with any backstory to speak of and had just grabbed the character sheet off of some forum (specifically searching "5e high damage builds," or something like that. the exact search escapes me). I know I should have seen the warning signs from here, but he's just not a very communicative person and I wanted to assume the best since I've had positive experiences with him before.

Come game day, all his interactions with the rest of the party or NPCs either involved him falling completely flat as a result of his character having little to no personality or trying to instigate combat with any NPC that looked even vaguely armed or plot-relevant. The peak of this behavior thus far involved his character stealing from a holy site and killing a tribe leader's pet fish (who he happened to know that NPC loved like a son), then serving it up on a stick to said tribe leader while the rest of the party were trying to convince the tribe leader to go to peace talks with a warring tribe. When combat (obviously) started as a result of that, his massive dexterity modifier let him outspeed everyone on the board by at least 5 initiative count (that was the lair action, by the way) and one-shot the head of the tribe, derailing the plot as thoroughly as he possibly could have. I managed to get things on the rails with the help of another player with antics involving the installation of a salmon-based religion and power word stun having to come out when my problem player (I really don't like to call anyone something like that but I'm starting to run out of synonyms, sorry) started to get feral next to the heads of 3 different countries during the peace talks, but it took a toll on both my improvisation skills and my goodwill towards that player. I understand having to pull out a spell with such a high level just to remove player agency isn't a great move, but I was starting to run out of options and the rest of the table deserved a positive conclusion for all the work they put in. 

Having typed this all out I realize that just the Min-Maxing isn't the problem here, but I'd like to take things one step at a time. Bosses are still a very necessary part of the campaign and they need to feel as mechanically effective as they do narratively. I can't just have one player beaming every enemy down, but I can't very well wipe the rest of my table just to give my min-maxer a challenge. I was thinking about giving the rest of the table magic items or designing enemies specifically against my min-maxer, but that just feels like targeting one player for having a different playstyle, and I don't wanna do that. Splitting the party every time I want to have a challenging combat also sounds tedious and again, targeted. I've consulted every resource I'm aware of (within reason) and I haven't found a great solution yet. I've also tried throwing hooks at that player to get them more focused on RP and engaged, but they seem to be ignoring that too. 

Also, for the people who inevitably ask why I don't just remove the player from the group, I don't really have that authority. We joined this group at the same time (we just bounce between campaigns depending on who's available that week), and I didn't start it, so I don't really feel comfortable disrupting what other people might see as a good thing for my own opinions, and I don't feel comfortable talking to everyone behind that player's back to verify my suspicions, especially when I used to share some of their less... desirable, habits (I've thankfully grown out of most of them, and am working on the rest). I've also tried to talk to them about their behavior several times, to which they always respond that they're busy (huh who would've thought lol). I can't really leave the group myself either as for personal reasons I don't really wanna throw on a forum, through no fault of my own, I don't have much of a choice when it comes to groups.

With that all said, what should I do? Should I design my campaign to artificially match that player's strength to the others, should I just try to ignore combat entirely, or should I do some third thing I'm too tired to think of right now? Thanks again!

Some people prefer optimizing over Roleplaying, and really, that's okay. All players are different. However, maybe have a chat with him? I just started DMing a group still relatively new to DND; I took over the group because their old DM sort of lost "control." (They were running around stealing things and killing random people). We took the entire session 0 to make characters, and I intend to continue making them a bit into session 1. The point being, maybe talk to him about the Roleplaying problems; however, do it while he's not being particularly active during a session (so he can't just say he's busy); talk to him about character development and the classic "what would your character do in this situation?" My only other thought was to help him enjoy it more? Maybe have him discover something the others couldn't during a RP.

Also, since he's not really being toxic, I'd say there's no real reason to kick him from the group.

It seems pretty likely that this player is just uninterested in the sort of game you want to run. Unless they're willing to change, it's never going to get any better, and they don't seem interested in changing. 

Given the constraints that you've placed on your available options, you don't seem to have any other options, except only run your game when this player isn't available, or schedule it with the rest of your players outside of the group's normal context.

However, is this player similarly disruptive in other games? The other GMs may agree with you about this player more than you think.

And yes, they're being disruptive. They were informed of the premise of the game and deliberately rejected it. They're taking actions in-game to instigate fights where none were needed. Are the other players having fun? Are you?

If it becomes a very big problem, asking the player to change their character is a valid solution. I say this for two reasons: first of all, they don't seem to have an emotional attachment to it, and second of all, they didn't even make it themselves. 

Before starting your next session, sit down with the whole group and ask if everybody's having fun in this game. Ask for honesty, and what the members would like to do or see more of. Just have direct communication with everybody involved, and don't necessarily point fingers. If you want to disguise your intentions, mention that you want to make sure the first time you're running a homebrew campaign is a good experience (technically the truth). 

Now here's the important part: listen to everybody's response. If everybody is legitimately having fun aside from you, then this player may not exactly be the problem. If everybody prefers a more combat focused game, then you may either need to adjust your style of story, or find a different solution. 

Or, if nothing is working out, a lot of people would tell you that no DND is better than bad DND. 

EDIT to mention: the question and discussion around what the players want in the game can serve to see whether the rest of the players view this Min Maxer as a problem as well. If they mention or insinuate that, you could use the group being together to try to talk to the player about changing their ways (even if it's just for this campaign). 

Start by talking to the player privately. Make it clear that this isn’t the kind of character you agreed on during session zero, and ask him to either adjust how he’s playing or create a new character that fits better with the group. Give him a fair chance to course-correct without risking feelings of betrayal.

If that doesn’t work, then it’s appropriate to talk with the rest of the group. It’s important to determine who the odd one out is: if it’s just you, you can either accept the situation or find a different group. If most of the group finds his play disruptive, then he should either adjust or, if he refuses, be kindly and directly disinvited.

It’s not underhanded to check in with the group — it’s necessary to figure out the next step. However, it would be underhanded to simply run games without inviting him, cutting him off without explanation. He deserves honest feedback and the opportunity to change.

If you absolutely cannot address the issue with the player or the group, then the only decent choice left is to accommodate him and continue playing as things are.

I've been there: new DM, homebrew mystery campaign, RP table...and the one min-maxer who caused friction. I feel you.

In my case, my player refused to admit to himself that he was a powergamer, and every attempt I made to suggest that my game might not be right for him got brushed aside. He constantly asked me about newer and more powerful builds/items/feats/exceptions, and he caused a significant number of combats because he just wanted to pick fights with NPCs. I did my best to make the game fun for him while not letting him steamroll me or the others, but boy was it was exhausting. It was also hard to balance, because his character was so much stronger than everyone else's. 

What I ended up doing was designing some encounters and homebrew items that let him revel in his power fantasy (which kept him happier and less disruptive). The rest of the time, I threw some hard counters that challenged him and the other heavy hitters. Enemies who used invisibility and teleportation, terrain that made stealth difficult, mages and lair actions that needed WIS/CHA saves, goal-oriented encounters where the victory condition wasn't killing or fighting but rather survival or rescue. Skill challenges, multi-layered objectives and puzzle combats allowed a variety of builds to shine, including his.  

Toward the end of the campaign he started missing more and more sessions, and it was clear he was prioritizing other things. It was fine. Although he did finish my campaign, he found a home with another online group with similar playstyles. All worked out in the end.

For you, I'd definitely talk to your min-maxer first about what he wants out of the game AND what you can/want to provide. Just because you get along well with someone in one context does not mean you make a good match as their DM, and that's okay! There might be compromises that keep everyone happy. And if there aren't...you're the DM, and you absolutely have the right to run the game you want, with the playstyles you want. One person's preferences don't override your fun. Good luck!

 I agree with Born_of_Fire74, pull the player aside privately and seek understanding and establish boundaries. Min/Maxers do not inherently cause problems in RP-focused games. This seems very much like a player who is not interested in an RP-focused game from what you have laid out.

Find out why they are doing what they are doing, explain why it is a problem in this campaign and ask them what they would like to do about it. Getting their feedback on what they think can be done is an important tool from motivational interviewing in eliciting behavior change. If you don't like their recommendation, you are not obligated to take it, but if they are the ones to propose solutions that you find agreeable, you will have their buy-in from the start which helps to ensure that the behavior change sticks.

I want to remind DM and players that this is COOPERATIVE game. Min-maxing is not the problem - soloing and ruining other players fun is.