I was busy keeping track of Black Tentacles and Crushing Despair's effects so I forgot about the second save for creatures who critically fail against Phantasmal Calamity, which could have stopped the two standing PCs from reviving the two downed PCs and led to a complete TPK. Just one of them failing the save would have guaranteed a dead party member, and they only had about a 20% chance each to succeed. After that they would have had to roll a 19 or 20 to escape the illusion thanks to their debuffs, which they'd need to get on their first attempt or lose both of the downed party members.
And now one of my players has pointed out Black Tentacles has been upgraded to Slither in the remaster so they should have been even more killed. With an extra 2d6 damage plus persistent poison every round I could have absolutely tpk'd them. This is so fucking upsetting. They should have all died and had to make new characters and the paladin player forced to write the backstory on why the help he requested took so long to arrive 
i just wanna kill PCs and everyone said this AP would kill loads but I trained my players too well and now I missed my chance to kill them aaaaaaaAAAAAA 
That's what you get for not using owlbears
Creature idea: The Hex Owlbear, it has a flight speed
Did you mean: Pathfinder's Variant Owlbear?
Holy shit imagine just stumbling upon one of those and trying to run, just to have it start flying
Unfortunately Owlbears are no longer in Pathfinder...
There are a few significant Drow in the AP, but we started after it was announced they were out and before Cavern Elves were revealed as the semi-replacement, so I've just being doing a running joke of mentioning that Drow aren't real every time they come up. The one they already met and killed was bugs so I more concentrated on that side of his accent, but they'll be visiting his hometown later and I think I'm gonna make all the not-Drow down there camp Bavarians who are very offended about being called Drow.