So the Whole Party is Dead Now
Nothing grinds a game to a halt quite like a Total Party Kill, or TPK. It’s never been something I think might happen, and usually figure that at least one person will be able to make it out alive. It’s a good idea to consider what you want to do about these situations in advance, otherwise you may spend a lot of time during that session trying to decide what happens next, or what happens with the story now that all the people in it are dead. I have only experienced one or two TPKs in my entire time as a Dungeon Master, and to be honest I only remember the details of one. I also lucked out on the scenario for it to happen in.
I had the unenviable task of introducing a brand new character to the party. I still struggle to do this in a non-contrived way, but in this case it worked out; the new character had been captured by strange creatures, stripped of his equipment, and locked in a cage in a dark basement. These creatures liked to capture people for later use (I can’t remember what that use was, but I’m sure it was something gross and awful. So dramatic!). The party entered the dark basement and moved to the cage. Before they could be warned, before they could equip the prisoner, they were ambushed. After a surprise round, and some lucky rolls on the enemies side, the party was all reduced to 0. In this case, I had them wake up 8 hours later, stripped of their stuff, in the cage.
5th Edition does have the nice benefit of saying that when someone is reduced to 0 you can choose for it to knock them out instead of kill them. This works well if you want to do what I did; say some time went by, and then let the party wake up, against all odds having been kept alive. This is good when the enemy is picking off heroes one by one, but what about a powerful damaging spell? I once almost killed the entire party with a fireball (I had forgotten what level they were, and put them up against someone much too strong). Thankfully two players survived with a couple hit points, but it easily could have gone to a TPK. What then?
A TPK is dramatic, and it will feel a little less jarring for the players if you are ready to respond to it. Have something in your back pocket, something that can be pulled out in any game, at any point in the story. Give them a moment for the deaths to sink in, then with a smile, move smoothly into what comes next, hopefully before they start talking about what character they’ll play next. Perhaps the party members, one by one, suddenly rise as ghosts over their corpses, and are trapped on the Ethereal plane until they can find new bodies, or find a way to get someone to bring them back. Another option would be to say that suddenly, all the characters “wake up” and feel as though they have been asleep, and everything they experienced was just a dream; but they are not their characters anymore, they are people in a totally different universe (alien? our world? children in an orphanage?). Let them play the rest of the game session like this, and near the end, have them wake up in their original character’s bodies on the resurrection table of a church, or the experiment table of a mad scientist. Maybe they learned something that has carried over after their “rebirth”.
TPK can be a great excuse to take a quick break from the story. It can let you explore something outside of the regular timeline of your game, since time doesn’t have to move the same when you’re dead. Consider having them suddenly rise 20 years later, after someone researched them and their quest and decided to cast the spells to bring them back. Whatever you do, try to have something ready. It is very surprising for players to lose all the characters at once, and you can really keep things on track by keeping the game moving.
Finally, don’t think that death always has to have a penalty, since the penalty is the sudden stopping of the character’s ability to pursue their goals. When they come back from the dead, give them something special or new, like an ability or some knowledge. This will help take the sour taste of character death away and make them feel even more heroic, having conquered the grave. I especially think you should do this if you do decide to give a penalty; if they have had their strength permanently sapped, maybe it has expanded their mind. Maybe if they are now cursed, they also have a strange blessing that accompanies it. Getting weaker is not fun on its own.