Crimson Throne Scarwall: about the insta-kills
So I'm DMing CotCT (my first campaign where I'm DMing) for my RL-friend group of 5 and they are currently crawling at snail's pace through Scarwall (hiatus occur often and they are pretty thorough which isn't necessarily a bad thing). Anyways overall they are honestly really stacked and one might say quite min-maxxed (25 points; Bloodrager has over 200 HP due to his familiar and dishes out really high damage; Brown-Fur Transmuter additionally doing big transformations on his party mates and exploiting Blood Money; ...). In short they only had very little difficulty in 98% of encounters.
Anyways I can clearly see that some of them are really attached to their characters and especially since it's so far into the campaign I imagine that they would just get more upset on a death. For the first half of the campaign I was honestly a bit fed up since almost every encounter was the equivalent of a wet paper towel and in comparison I'm a guy who's the most intrigued of challenging battles instead of highly optimized ones. I still have the same opinion today but I also have gotten more hesitant to throw something truly life-threatening at them which will just make them mad (even though I personally think that such encounters belong to the coolest).
In Scarwall there's specifically two instances of insta-death moments: the Banshee on the roof-area and the Demilich who also is a chained spirit (thus required). I worked through their stat blocks and generally think that they have the potential to be really cool fights. As you can probably already tell, there's one issue with both of them: both have at least one ability which can just instanly delete your character.
I already have warned the players that in this dungeon there are such encounters which can just instantly throw your character's spirit into the afterlife (not sure if they truly got the memo though or just don't want to comment on that). Anyways I just don't want those encounters to just happen out of the blue so it doesn't look like I'm bullshitting them.
I already thought about implementing a build-up for each of them and hinting that they have such abilities and it would be unwise to go in unprepared even for a steamroller of a party that they are. For example the two DM-PCs from the brotherhood could warn them that past investigations from the air all failed because the roof-spirit's scream lead to most of them dropping into the lake like a sack of potatoes. On the demilich the concept of this enemy basically is surprising a overly uncautious and them facing the consequences. Since the arcanist has extremely high knowledge, he could notice that something's not quite right about that skull. Also I thought of perhaps hiding a single(!) scroll of resurrection somewhere in the dungeon. What would you do? Are you generally more unbothered about (rare) save-or-suck abilities?
TL;DR most of my players are very attached to their characters and I'm highly hesitant to throw extremely deadly enemies at my party even though I personally enjoy such encounters.