I has a group that played largely published modules, and we tackled the behemoth that is Dungeon of the Mad Mage. Now our group was only what I could call some slapstick idiots and one very grumpy, long-suffering cleric.
The campaign had been a romp full of chaos, intentionally setting off traps, and using my swashbuckler's frankly unfair persuasion score to get out of most encounters with anything remotely intelligent. I even swan dived into a portal to the Astral Sea for funsies that lead to a couple of weeks off-book to get us back on track.
But floor 14 ... floor 14 with the Weapon of Mass Disintegration. We'd found all the keys while clearing the floor and we pretty beat up from the encounters. The Magic Mouth starting the countdown delighted most of us - we were chaos gremlins after all, and whatever happened was going to be great!
Boy, were we lucky to have our cleric - a man who had the foresight to choose Life Domain and take a few levels of sorcerer. As the rest of us laughed with glee and anticipation, he ran around the room twin casting death ward on us.
That surly little cleric was literally the only thing that kept us from a TPK in that moment. Of course the only thanks we could offer him was letting him carry the control rod for the death slaad we kidnapped along the way.