As with all editions of D&D, the lethality dial is set wherever the person designing the encounters chooses to set it.
"Balancing across multiple encounters" in 5e is just as ridiculous as the fear rules in 2e. And like them, good DMs throw them out the window.
But there shouldn't be "multiple...
It's interesting that in Lovecraft's short story Dagon, the only threats to the narrator come from all too human German navy, and himself. The giant deep one he witnesses makes no threatening moves whatsoever.
Death by massive damage. Continue to attack downed characters. Disintegrate, stoned and other insta-kill spells. Stun.
As above, plus control abilities. Try AoE stun. Blindness effects work too. Can’t cast healing word on something you can see. A simple fog cloud works to counter it.
You said...
It can be any kind of organic growth on the hexblood’s head. It doesn’t have to actually be elder. It’s just something to make hexblood’s easily identifiable so the commoners know who to burn. Choose what suits your character’s theme. Eg bone if you are necromancer, mistletoe for a druid etc...
Yeah, the trouble with being too serious is the seriousness itself becomes a joke. Same is true for excessive grimdark which 2e Ravenloft also suffers from - Warhammer parodies that.
The original Ravenloft adventures are very much based on Hammer movies rather than the book. The Strahd romance...
As someone who extensively played 1st edition, that’s just the myth. PCs rarely died in my experience unless they did something really stupid. Well designed encounters and sufficient information available about death traps if players looked for it and everyone lives. The reputation for lethality...
I will point out again: horror does not depend on the fear of death. Any action adventure game or story threatens the life of the protagonist, without being horrific. Dying isn’t scary, everyone does it.
As for horror, Marvel Comics* does it regularly, superpowered protagonists don’t make it...
So far they haven’t made major changes to non-core species, so I suspect it will still boil down to “you know change self and Hex, and can spy on people with an old fingernail”.
The only “tool” you need in a GM toolbox is being a good storyteller.
The original rules about mental illness were replaced because they stigmatised mental illness - something Lovecraft reasonably feared, given that he, like so many others, struggled with mental illness himself. As do many...