I myself do not know if this is where I should be asking this, but I would appreciate it if I could have some insight from the more experienced GMs out there.
I have a player in my D&D group, and also happens to be the best out of the lot.
However his attitude is extremely negative when it comes to rulings inside the game, "negative" may sound a bit harsh but from his point of view he is most probably doing the right thing.
Let me give you some examples instead,
Whenever a situation calls for the GM to decide something that is vague or not clear in the book, he will go all out finding every single sentence in the book (or point the lack thereof) that would counter me and try to establish it as the ruling.
For example, he as a rogue tried using cunning action to hide behind a tree after popping out and attacking from the same tree and getting successful sneak attack from the advantage of unseen attacker. I ruled out that his cover was blown and that hiding on that same tree would not work anymore. I burned a majority of the time trying to calm his accusations of me breaking the rules and invalidating his character when his stealth would clearly beat their perceptions. And he lost enthusiasm and faded out of the game, including the rest of the players caught by his gloomy aura.
Another time he tried sneaking with invisibility and, again, accused me like above when I had him roll stealth to muffle his footsteps and according to him I had invalidated his "High passive stealth" because, according to the book, that is what passive stealth is about.
I brought a mummy with a "Good" alignment, sort of a helper NPC. He proceeded to kill it under the assumption that "The monster manual says that mummies are all lawful evil and thus you are wrong". This also happens on many more occasions where he assumes certain situations are going to always go according to his plans because his understanding of the rules are always correct and there cannot be anything but "Rules-As-Written" in Dungeons and Dragons, otherwise this would not be Dungeons and Dragons.
Kicking him out of the game is my last resort, I really need some kind of alternative to make him understand that the GM might sometimes rule or interpret something differently than your understanding. I feel like my creativity is limited because I have to spoil him to beat him at his arguments (Monster X does Y because of Z reason).
The rest of the players usually handle my rulings pretty well, and if they have a question, we discuss about it after the game.
He also seems to not think about the repercussions of the same rulings that get applied to enemies too, at one instance he declared "Bullshit" and went into a silent rage after getting ambushed by invisible enemies that I let sneak past him with their passive stealth as per his request of how it should have been handled. I could have brought that they would be encountering invisible enemies, but that would have spoiled the game for him and everyone.
I always look at maintaining the perfect balance from a neutral point of view, but I can't help getting bashed by him everytime I try something new.
I am at a loss, does anyone have any experiences with players like him? If so, how did you handle it? How do you exert your power as a GM without sounding like a major bully?
Is there a way to counter the argument of "It's not D&D anymore" if I make a single different interpretation of a rule?
Best Answer
My suggestions, coming from the other side of the fence where I (and some of the other players) feel that the DM plays a little too fast and loose with the rules, and makes changes to things that we think ought to be "canon" for the well-known world we are playing in:
1) Be willing to consider that the player may be right. Allow him to make a brief argument referencing the rules. Then make a ruling. Make a mental note of how often you rule against the player versus how often you change your mind and agree with him, and try (later, outside the session) to assess whether you're being particularly harsh and/or truly weakening one character's abilities relative to the others'.
2) Be firm if you still disagree with him. If he still disagrees with your ruling, tell him, "I need to ask you to go with the DM ruling for the moment and we can discuss it more later outside of game time, to figure out how we'll play this type of situation in the future."
2a) Try to offer the player another way to reach his objective. Say something like, "Look, the rules say that you give away your position if you attack from hiding. If you then, in full view of the enemy, duck behind the same tree, they are going to know where you are, even if you are so well hidden that they can't perceive you. Thus you do not get the advantages of being hidden in that case. Now if on your next turn you stealthily move to the next tree and hide there without being noticed, and then attack, that would be unexpected and give advantage."
3) Ask players not to use the Monster Manual at the table, and to avoid using metagame knowledge about monsters. That said, try not to mess with well-known monsters in a canonical setting without a really good story justification. If you're playing in a canonical setting, Mummies are going to be something that most adventurers will know the legends of, and the way that Mummies are described in this universe really does preclude a "good-aligned Mummy". If there's going to be a good-aligned Mummy, there should be a good story to go with that, to say how that happened contrary to the usual Mummy creation process, that the PCs have at least been given hints about. Otherwise, yeah, it's pretty appropriate for a PC to automatically kill any Mummy he comes across on sight. They will know the stories....
Note that the 5e MM does say (page 7 if need a reference for your rules lawyer):
However, unless there is a good story behind the anomalous alignment, and your PCs have access to clues about that story, I think it would usually be better (and annoy your players less) if you either make up a new monster that isn't in the MM, or be clear that you are playing in a non-canonical setting and using monsters that don't match the descriptions in the MM. Even in a canonical setting, you can play variations on less-legendary monsters, but be clear (out of character) with your players that this is what you are doing. In all cases, allow the players relevant checks to recall some in-game, in-setting lore about the monster you are actually playing.
For example instead of just putting in a good-aligned Mummy you could say, "You see a medium-sized humanoid, wrapped in bandages. Make a religion check". Tell everyone with a low score that they think it's a Mummy. Tell whoever got the highest check, "Because of [some detail that they can perceive] you think this might not be a true Mummy but rather a Pseudo-Mummy. Pseudo-Mummies are created by a different process than True Mummies and in some cases can maintain their pre-death alignment." If you want, you can go into the process more, or you can just say that the character doesn't know any more than that. Now you have a good-aligned Mummy that your player shouldn't complain about.
4) Consider having a talk with the players about what game everyone wants to play. You have a conflict in play style with the "rules lawyer" player. Do the others also want to play "his" game, or do they prefer your approach? Can whoever is in the minority live with adjusting their expectations to what the group as a whole prefers? Can there be some compromise?