Death is an integral part of the game. Without it, challenges become bland and boring. I compare this to cheat codes in a solo computer game. As soon as you have these, you will use them, then at some point, when the novelty of the cheat code is off, the game feels less and less compelling and intersting. Up to the point where you stop playing it because you feel that there is no challenge.
D&D without death is exactly like that. With the possibility of death, comes a thrill, an expectation and fear. Yes sometimes an early TPK can be frustrating, but with these comes also the feeling that when the group do survive, thrive and succeed, the feeling of true accomplishment and the pride in knowing that your success in these are entirely on your shoulders and not those of the DM.
All this to say... let these characters rest in peace. Make an other group to investigate their death.
While DMing today, a PC died today, 2nd level on the cusp of 3rd. It was partially good DM rolls, partially poor planning. The battle:
The PCs attacked a xvart lair then left to take a 1 hour short rest. Xvarts aren't stupid, and they regrouped the bulk of their forces in a central war room while directing a force to trail the PCs and block any escape. Rather than infiltrating the lair and taking it room-by-room, 5 2nd level PCs faced a very deadly encounter of 13 alert xvarts, 1 xvart warlock, and 1 giant tick. Given the PCs had killed a sacred whiptail centipede, destroyed the centipede hatchery, and insulted their deity, this wasn't a battle where prisoners were going to be taken. It wasn't a glorious death that anyone will write stories about.
I generally don't like pulling punches in my games and roll in full view. In doing so, I can't fudge away a character death when the dice do their thing. I'm not inclined to because if players catch on the DM is going to intervene every time death is near with a convenient plot device, it'll cheapen the experience.
And the typical, "Oops, you're dead! Just make up a new character, come back next week, and we'll handwave that the other characters trust you with their lives so we can keep going," isn't a cheap experience? If the characters are tossed aside like used tissues when they die, clearly they are pretty cheap, no?
Whether this would "cheapen the experience" depends on why your players are at the table. There are some types that would find rescuing PCs to be an issue. But, for many others, it isn't an issue. You should ask your players what they really want. For example, for some, the resuting narrative is what is important. The narrative sucks if it becomes, "I played the characer for a few sessions, but then just died in a combat we didn't really care about." The charcter sheet gets crumpled up and tossed in the recycling bin, to be forgotten in a couple weeks. It becomes cool if the narrative is, "I fell in combat, and then this awesome thing happpened and I was rescued form the edge of death!"
After all, why roll in combat when you know the DM won't really let you perish, perhaps because you wrote an awesome backstory that fits with the campaign?
Look at your life for a moment. There are things in it you care about, yah? Friends? Family you care about? Pets. A home you are attached to? A job that keeps you going? Aspirations for things you want to do in the future? Is your life really the only thing you have to lose? No? Then why should it be the only thing a character has at stake?
When you have that backstory, you have a key into things the character cares about other than just their own life.
Should I intervene, again, though, with another convenient story plot device given I just did so? I've got ideas, but it feels contrived to do this twice in a row and so quickly.
So, consider - soap operas are perhaps the most successful genre of television ever created. They are entirely contrived, but to many, they are compelling and satisfying.
What's more interesting: 1) You're dead. Make a new character, or 2) You fell in combat, and the xvarts carried you off to be offered as the first meal to their new sacred centipede, soon to hatch from the one last egg the PCs missed. It will be a slow process of the centipede eating you alive, unless either the party, or you, find a way to escape this fate....
So, I just absorbed the rules for a new game. And, in this game, it is explicitly stated that the GM cannot kill characters. Characters can get beaten down until they are forced out of a scene, but whether that kills the character is entirely a player's choice.
Character death is only a valuable thing to some players. Make sure that it is for your players before you choose what to do about death.
After all, why roll in combat when you know the DM won't really let you perish, perhaps because you wrote an awesome backstory that fits with the campaign?
Having some element of plot immunity doesn't mean that you shouldn't be rolling in combat. That's not a necessary conclusion.
All you have to do is choose to KO them in melee combat rather than kill them and you don't even need to fudge that. Then you have other story options that come up that can still involve their awesome backstory that fits with the campaign other than creating a new character (with, perhaps, a less awesome backstory).
Keep in mind, you chose to have the xvarts fight to outright kill. You can choose to change that.
So, I have always argued, 'Nope, let the side fall where they may. Character's dead.' However, for the first time recently I 'cheated' and didn't kill someone. I didn't hide the absurdly high damage roll, but I glossed over the specific special rules which meant that, in this particular circumstance, the roll should have meant insta-kill, no death saves, done.
It felt wrong at that moment to just kill the character out of the blue with a ridiculous roll. I'm still not sure how I feel about it.
