Ok, guys I think I ****ed up big time. 

So my players had an encounter where there were tasked to clear a manse from an evil cult. They looked in the perimeter and rolled a 26 on perception. I told them that they see enemies they normally wouldnt have seen etc. When they decided to throw a fireball at the place I decided to roll with it. That is the part where i ****ed up. 

some of the creatures died because of the explosion and some were trying to run out of the building. Problem is that i put them out of the manse at the start of the initiave so all 40 enemies just barelled through them and they were barely escaping with 1 parrty member dying and getting taken away. In my opinion that was unfair and i should have let the enemies come out a turn later than them or just let a few of them come out every turn. 

One of players that is heavily engaged in combat now wants to leave the campaign because of this unfair encounter and i agree that it was unfair for them. I am afraid of my dnd session crumbling when he leaves because of the roleplaying aspects he brings. Also everyone was frustrated at the end of encounter and had muted themselves when it wasnt their turn. 

Do you think i should redo the encounter from the point where they threw the fireball and let the enemies not be outside of the building all at once?

Not unfair at all. This is just my take on it anyway and others may feel differently. They did not have to toss a fireball into a mob like that. You "just rolling with it" was not wrong. There have been several times in my games where I set up an encounter or whatever where I assumed that the players would go about it as specific way, only to end up having some of them all pissed off and in some cases walk off. If the players see a mass of baddies and want to act... well foolishly. Then bad things can happen. The game is not intended for everything to go in the players favor. Thats just part of it. Whats done is done and I think you should move on with it. Even create something from it. Dont give in to upset players who cry out that it was unfair. You did not force them to act that way.   

Players can not pretend they didn´t see the DM fumble like that.

Own the situation and offer something to the characters as an olive branch, a good amount of XP for surviving the encounter and an equal lvl PC to the player that had their original character die.

You are playing as much a as they are and are allowed to make mistakes as I´m sure they do.

Redoing an encounter opens the possibility for them moving forward to just ask again for a redo if something doesn´t go as they intended an puts them in the head of the table.

I would generally retcon rather than redo, but admitting to messing up and adjusting things is something DMs have to do every now and again.

What part do you think you stuffed up? The cultists running away from the fireball? I’m not sure I’m following why you’re 100% convinced that you did the wrong thing. What did the players think they would do? (Honestly, did they tell you what they thought would have happened)?

Problem is that i put them out of the manse at the start of the initiave so all 40 enemies just barelled through them and they were barely escaping with 1 parrty member dying and getting taken away. In my opinion that was unfair and i should have let the enemies come out a turn later than them or just let a few of them come out every turn. 

Is the problem that the encounter turned out to be too hard? Or is it that from a roleplay perspective, if the villains had been played as they would/should have acted, they should not have all run out of the burning building? Did you violate rules of movement to just get them all out, or did they all move their dash speed as their NPC stat block indicates?

If you ignored in-character motivations for the NPCs -- for example, some of them would rather die burning in the manse than leave it -- then maybe you should not have done it. If you ignored the D&D rules, giving them an incorrect movement speed to get them all out at once because you were being lazy, then maybe you should not have done it.

But if you think it was unfair just because it led to a hard challenge for the party well... I'd tell the players, welcome to D&D. Don't throw a fireball into the middle of a 40-bandit stronghold without expecting the whole thing to come down on you. Next time try stealth.

You want to keep the group together right? Maybe it was their mistake like some suggest, but that doesn't help you keep the group together. I would talk about it so people can get their frustrations out and find a way to 'fix' the dead player character in the next session. Maybe they are just really heavily wounded or maybe their death can be reversed in a cool in-game way. One way or another, I would continue the adventure/story without a redo. Can't explain why but a redo just doesn't feel right. 

Is this the first player death in the campaign? Did you discuss player death before hand? 

If they rolled a high perception and saw more than they normally would, and still thought that tossing a fireball in was a good idea... doesn't sound like they thought it through.

As long as [like Bio] says you didn't break the actaul "rules" this sounds very self inflicted by the players... 

Id talk about why there were annoyed and sort it out as people no characters. But i wouldn't redo and id be a bit firm about it being self inflicted wondering what they expected to happen...

Ok you just trigger me. You have a dead PC on the field. If I reading the post correctly. Dead PC is being dragged away. Smart PC is trying to cut their way out to run away. Other pcs are fighting for their lives. And everyone is ticked about it. This sounds like  penalty flags for both sides. So since the dead pc maybe your fault due to what ever. A minor retcon is order. Retcon. Dead PC is at zero and 30 feet away. The bad guys have fled. Everyone else has the current hit pts as of last session. 

But it also sounds like you have players upset about other things. I don't know your group. But my rule unless a dead pc is on the field, no ret cons. And I only retcon if the death was 70% my fault. Q1 how do you handle deaths? Are the PC Joe Blow with 2 weeks to retirement/30 days short aka death is around every corner. Or I am the star of the TV Show aka PC only dies if the player wants to? Q2 Did you discuss deaths in session 0? Q3 Are any players goobers? aka I am in control of the game not the dm. etc?

Perhaps you could take a page out of the old school comics. The PCs only *thought* the dead PC is dead. It turns out he is just captured and very hurt, but wakes up imprisoned. The other PCs now have to break him out. It'll depend on how mad the players are if you can pull this off.

But I think the key here is you need to do a "Session 0" - again, if you started with one, or for the first time if you didn't. Start by saying that clearly you and they are not exactly on the same page in terms of campaign expectations, and you want to be on the same page with them, so let's decide things like how lethal we want the campaign to be, how hard a challenge the players are comfortable with, whether they want there to be consequences up to and including death, and whatnot. After they lay out their side of things and you lay out yours, see if you can come to an agreed-upon answer to these questions. If you can all find some set of house rules that make you all happy, then you can move forward.

You could possibly also do this as one of those movies where the person sees visions of his or her death and then the events that domino-fall into the death happen later. You know the ones where a group of people is driving down the highway and there is suddenly this huge crash, 10 car pile up, everyone in the car dies, and at first you think it is really happening. Then the passenger wakes up and it turns out it was just a "vision". Then the events start to happen as in the vision and the person who had it tries to change things so the crash doesn't occur.

Maybe one of them had a vision of what would happen -- they talked about fireballing but instead of actually doing it, the cleric's god gave him a vision of what will happen if you throw that fireball. Go back to right before the fireball, the cleric is on the ground and the others are trying to wake him up. He then can tell them what he "saw" and that maybe they should try a different plan.

This hole thing just makes me think that there is something inherently wrong about rolling death saves as a player.

It sort of handcuffs the DM and has the finaly say about an important aspect of the story, life or death of a character.

Once everyone sees the result of that roll thats it and you can´t avoid to be cheap if you make it come back.

That should be reserved for mid, to high level characters (in D&D at least but in many setting should be just impossible)

that also have to go get the body but the all know and have to avoid metagaming.

It doesnt let the other players make the wrong desition because they all know if that characters is for sure dead or alive. 

This depends on the situation. I don't think you can retcon it and it probably isn't appropriate to do so since it will break immersion to an extent that might not be salvageble.

Here is what you appeared to say:

1) Party is clearing a manse of an evil cult.

2) They arrive, roll well on perception and notice several enemies outside the building.

3) They decide not to scout further, assess numbers, come up with a plan. Instead they drop a fireball into a possible hornet's nest not knowing how many opponents there might be or where they are located.

4) After being alerted by the fireball, enemies flood out of the manse escaping the fire.

5) Party is overwhelmed by the unexpected level of opposition all at once. Think the encounter is unfair because there are so many. Some players may want to take their characters, go home and not play because it was so unfair.

They didn't scout, they didn't know what they were facing, they didn't take any other actions (in your description), they dropped a fireball to stir up the nest and get an immediate hostile response. Ooops ... there were more of them than we thought ... waah. Is there something missing from the scenario?

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Can you retcon this? Not without replaying it and pointing out the players all the things they did wrong.

Did you have a session 0 and go over how the game works? Did you promise that every encounter the PCs would ever face would be easily defeated by combat no matter what actions they choose to take? Basically, what sort of game did you and the players agree to run or was this something you didn't discuss?

A DM creates a world, the characters interact with it.

However, in this case, I think your mistake was not starting initiative with the casting of fireball. That was the opening of combat. That was the first hostile action taken. Since the defenders were not aware of the characters, they would be surprised during the first round of combat. Starting it this way lets you (the DM) evaluate how the combat is going so you can delay creatures joining if you want to make it easier.

On the other hand, most creatures using the dash action will have a movement of 60'. Depending on the size of the building, they will all get out within one or two combat rounds. However, they will likely emerge on all sides of the building through all the doors and windows ... not all of them will likely be facing the characters at the end of the first round.

The party could still be overwhelmed. They obviously weren't expecting 40 enemies to emerge and attack. Having the enemies move from the house on the first round after surprise gives the players a chance to assess what is going on. When they see far more enemies than they expected coming out they would have an extra round to choose to flee or possibly fire another fireball to thin the numbers further. Also, with 40 opponents, you don't want them all on the same initiative. A high initiative and some good rolls could wipe the party before they get a chance to do anything while a bad initiative and a fireball or two against clumped enemies could go the other way.

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However, you can't really replay it effectively ... though if you and the players really want to you could make the combat that just occurred be a vision given by some patron/diety showing the characters that if they take this course of action, it will not work out well ... then start the players at the beginning and see what they choose to do .. but that is less than ideal.

You will need to have an out of game discussion with the players about the situation. Explain that you probably should have started initiative at the point where the fireball was launched and not just after all of the NPCs had fled the manse. Part of the problem is the characters poor choice of tactics and part of the issue is the point where the DM chose to start combat so both the DM and the players should learn from the experience but that can only really be resolved by an out of game chat with the players where the DM explains what they did wrong and what the players could have chosen to do better.

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On final comment, did you consider the encounter reasonable for the party composition and levels? Encounters can always go wrong. I ran one last night which went back and forth with two characters down at one point making death saves. It seemed to swing from being an easy success to near TPK as dice rolls went from good to bad and back. However, if the encounter was reasonable  (though 40 opponents is a lot for the action economy) then the only real issues were the player strategy/tactics and the DM choice of when to start initiative since it would give you more control over how the battle developed.

On final comment, did you consider the encounter reasonable for the party composition and levels? Encounters can always go wrong. I ran one last night which went back and forth with two characters down at one point making death saves. It seemed to swing from being an easy success to near TPK as dice rolls went from good to bad and back. However, if the encounter was reasonable  (though 40 opponents is a lot for the action economy) then the only real issues were the player strategy/tactics and the DM choice of when to start initiative since it would give you more control over how the battle developed.

I don't think the 40 guys were supposed to be one encounter, though. There was a building with rooms. Classically the rooms isolate the enemies into several encounters of manageable size. If the party proceeds through the building in a logical progression without making undue noise, they can normally divide-and-conquer, taking each room as a separate encounter, or maybe "aggroing" (to use an MMO term) a second encounter from an adjacent area, but not having the whole entire "dungeon" come down on their heads at once.

The problem the OP DM had was that they dropped a fireball into the middle of the building, and all 40 enemies, which were probably 5 or 6 or maybe even 10 different encounters originally isolated by walls, doors, and even building levels, got combined into one mega-encounter. As a DM, my general feeling on this is, if it happens, it happens. Especially if I have isolated the enemies into small "digestible" pockets and the PCs do something to bring them all together into one place. Actions have consequences. Don't open with a fireball alpha strike in the middle of a base when you haven't chipped away at the encounters next time.

I wonder if the OP was using a gridded map, or if this was theater-of-the-mind. On a gridded map, if you spent movement for each enemy and they had to walk out of doors or jump out of windows, I doubt the 40 enemies could have all brought their attacks to bear on the party at once. I also doubt, unless it is a very tiny building (but the OP calls it a "manse", so it is probably not small), that all the NPCs could have gotten out of the building in the same round. With theater of the mind this kind of thing is often fudged, but I bet on a battle mat it would not have been possible for them all to just run out and start hewing down PCs. So next time you might want to use a map grid to just count everything out and make it a little less chaotic and arbitrary.

But before doing anything you really need to have (or repeat) your session zero and make sure you and the players are of the same mind about consequences and the fact that if they do something crazy, yes, they might "blow up the world" as it were.

Quote from Deodorierer >>

some of the creatures died because of the explosion and some were trying to run out of the building. Problem is that i put them out of the manse at the start of the initiave so all 40 enemies just barelled through them and they were barely escaping with 1 parrty member dying and getting taken away. In my opinion that was unfair and i should have let the enemies come out a turn later than them or just let a few of them come out every turn.

Do you think i should redo the encounter from the point where they threw the fireball and let the enemies not be outside of the building all at once?

 Redoing the encounter in that situation is completely fine, if you feel you were unfair to the players.

I've redone encounters twice before, one time while playing Storm King's Thunder as the party aggressively stumbled into four stone giants who completely outmatched them and had killed half the party just by tossing their boulders to meet their charge. I let the rest of the fight play out for another round or two, and then turned to the cleric player saying their habitual "I am preparing for a battle to come"-prayer had been answered with a vision of what lay beyond those hills, and how that fate would play out if they followed it this day. They weren't close to level 10 yet, but the first Divine Intervention is free. The party snuck up to confirm the giants being present and took a considerable detour instead.

The other time it was deliberately propositioned by a player, as part of their laying a strategy for dealing with a potential siege. They literally asked if we were going to spend the entire session in analysis paralysis as they planned for what they could (with the divination spells they had availbale), or if we could instead play out a scenario. We opted for having fun with it and played out a "reasonably worst case" fight which they lost, and then did the entire thing over with a minor tweak in their plan and me scaling back to the actual encounter.

It doesn't sound to me like you did anything wrong. It's pretty hard to tell from the story though. It sounds more like a player who is sour things didn't go their way threatening to break up the group. To put it in more bitter terms, they're stomping their feet hoping you'd accommodate them because they think things should have gone differently.

Now its hard to tell from text on a webpage, but if that was true i would ask the player to adjust their intentions or leave. But that is me. I wouldn't let anyone hijack my games like that. But again, this could be me not understanding the full scope of the situation. 

What's most important is the fun of your players. I would advise you talk to all the other players about it one on one. Get their input into the situation. Talk to the player who said they're going to leave and try to resolve the issue.

If after all of that you think the best solution is to retcon things. That's a choice for you to make. Many DMs will advise you that its a bad thing to do. Many will say its totally acceptable. What matters is you do what's best for your group.

What's most important is the fun of your players. I would advise you talk to all the other players about it one on one. Get their input into the situation. Talk to the player who said they're going to leave and try to resolve the issue.

I agree... Talking about it like calm adults is the key.

However, I would be concerned as DM that we do not set the precedent that any time something happens that the players (including the foot-stomper in particular) do not like, they can just threaten to quit the game and force a retcon. I would make it clear that this can happen once, ever, period. That we will establish some ground rules for things such as just how lethal is the campaign. And then after that, no retconning. What happens happens.

They also need to understand that there is no particular reason why the enemies would make it fair. The DM isn't supposed to be trying to "win" against the players, but the monsters absolutely should be trying to win against the party. If the players can't handle that then... well if it's me, I'd say, "Find a new DM."

EDIT:

Thinking about this, one way I might approach it is, "You get one retcon ever. Would you like to use it now? Keep in mind that you will not be able to do this ever again. Or would you like to accept what happened and hold the retcon in reserve for another time?" This way, they can have their retcon this time if they want, but they know the option is not open continuously whenever they don't like an outcome of an encounter.

Quote from BioWizard >>

What's most important is the fun of your players. I would advise you talk to all the other players about it one on one. Get their input into the situation. Talk to the player who said they're going to leave and try to resolve the issue.

 

I agree... Talking about it like calm adults is the key.

However, I would be concerned as DM that we do not set the precedent that any time something happens that the players (including the foot-stomper in particular) do not like, they can just threaten to quit the game and force a retcon. 

 This is a great point as well. You don't want to teach your players that when they dislike something they can threaten you to get their way. It will quickly dissolve into you not having fin and may eventually lead to you not wanting to DM anymore.

Your players should try to resolve things in character. For one to turn to you out of character and say they didn't like what happened and will leave the group of you don't fix it. That's not good RP to me, and is a red flag in my books.

A game group can't survive if the players are miserable, or if the DM is miserable. One way or another, this needs a conversation about priorities and goals for game play. Otherwise, as Matt Colville and others have said more than once, "No D&D is preferable to bad D&D."

Never redo encounter like that. Seems like you had put some serious thought to it and players total failed.

Say to your players to suck it and inform them that "it" can happen again. Builds tension.

E: You did not fail, you just incorporated to players that Shit happens if they do shit. 

I'm in the: "the DM didn't fumble camp" here.

The Players acted stupidly and illogically, but I think there's a reason for that which doesn't make it entirely their fault either. There's an expectation in a lot of D&D culture today that the Players can't fail. Players believe that all the encounters are balanced, and that if there's an encounter, then there's a way for them to win. That seems to be the default expectation.

That's a style of play - and if it's the way you want to run your game, that's 100% fine as far as I'm concerned. But if it isn't the way you want to run your game - if you're prioritizing the verisimilitude of the world over the ability of the Party to be able to win all encounters, then the Players need to be aware of that as well.

It's an excellent example of the need of setting up expectations of how the game is going to be run, in a session zero.

You need to let the Players know how you stand on the internal logical consistency of your game world, Character mortality, and realistic consequences of their actions. And they need to let you know how they feel about that as well. You need to come to an agreement on how your group is going to handle that.

It's that compromise position that will tell you if a "redo" is right for your group. If you all agree that you want verisimilitude and plausible consequences, then don't do the redo. If you all agree you want a more light entertainment pizza and beer kick in the door, kill monsters, get loot, have fun on a Friday night while relaxing type of game, then a redo is warranted.

You need to know what you (collectively) want, and what are the conventions and expectation of the group are, before you can decide whether you want a redo.