speaking of FoF... [SOME SPOILERS]
Hooo doggies!
That was my only TPK. The party had been wiping the floor with everything in the place. I tried to adjust the challenges (add a few orcs, give everything max standard HP, etc.). Nothing worked. The rogue got killed by Yellow Mold, but they got him raised no problem (was actually a nice side adventure in the trip to a city with a powerful enough cleric).
So it's taking a few sessions to get through the thing and between gaming nights, I ask the group via email "Hey, you're saying the module is too easy. If you want, I can adjust a few upcoming encounters. I'll boost the rewards appropriately, of course; but there'll be some greater risk."
"BRING IT ON!!" was the consensus.
So, for starters, I left in the roper (optional encounter). The thing is CR10 & they're 6th level (I know the module is meant for a lower level party, but they kept taking side trips and coming back, so they got "outside" XP. One of the reasons it was taking so long). "This should be good!" I think to myself and spring the roper on them.
They cleaned its clock.
So now, of course, I'm looking ahead to the dragon encounter. It's CR4 by the book & they just wiped out a CR10 creature with SR! Since they're now closing in on 7th, I boost ol' Nightscale to a CR8 (Young Adult?) and work out some BADD tactics.
Only the rogue got away.
...and that's because I lost track of how far up the ladder he was for one round. I could've had the dragon chase him down the mountain, but that would've been vindictive and I didn't have the heart.
I was stunned. This group was
pulverized by this dragon. Between it casting Mage Armor on itself and using Darkness, they were screwed. It took less than 10% of its hp in damage. I felt really bad about it, but I couldn't backtrack. I stuck to my guns & the campaign basically ended. I'd warned them repeatedly and they kept asking for more. *sigh*
Sometimes you just have to kill an entire party to get players to use a little risk assessment. We're playing a new campaign in new setting now. One of the others is DM-ing this time. It's fun and I will probably run the next campaign, but I notice folks are a little more cautious in this campaign than the last.