Exotic Almond

Oh my gosh I've been waiting to be able to rant about this!

Ok, so ravenloft itself is made up of many small demiplanes called domains of dread(this is all official content btw) The Dark Powers (yes, they're just called "The Dark Powers" never explained) trap people of immense evil (for example murdering a sibling during his wedding with the intent to steal his wife and use his blood to turn into a vampire). I don't know why evil things trap evil people but whatever. These domains are tailor made to torment the "darklord" of the domain (they're not always in charge but usually are.) They can control whether or not other people can leave their domain by opening and closing the mists but they can never leave. Only about 1/100 people born in these domains (which can range from the size of a building to an entire continent) have souls. This is because new souls can't get in and old souls can't leave so they endlessly reincarnate as new people. Sometimes The Dark Powers randomly kidnap capable adventurers and put them in horrifying scenarios for their own mysterious reasons.

My campaign specifically is about a group of adventurers who got kidnapped (except for one who escaped his domain of birth and yes he has a soul) and they are currently trapped in a domain that includes just a house (The House of Lament). After this I'm going to have them go to a haunted orphanage at some point and am definitely going to have the party and the character who was born in one of the domains go back home for trauma at some point (it's A-OK with the player). Other than that I'm going to have to come up with stuff. I'm friends with all these people so I know their basic fears and will use them to the best of my ability to make a spooky atmosphere.

TL;DR: Ok, so I just looked at this and apologize for the hyperfocus rant basically stuck in a horror dimension and trying to escape, looking for ideas for more spooky places.

THATS EPIC I love it so much…

It reminds me a lot of the Magnus archives, if you know what that is. Also um character trauma!!!  

Hmm…more spooky places…

complete and utter darkness

something that messes with their memories (either makes them…like…relive one of their worst moments, or takes away memories and they can’t remember who they are while in it?)

something where they become the monster

puppets

 Hmm idk if those will help but that sounds so fun, you guys better have a blast

The memory one is actually a canon domain called blutspur, it features mind flayers and incomprehensible alien technology. Fun.

Puppets is something that I didn't even think of even though I love spooky puppets. Will definitely use that one!

Darkness can be hard because so many character races get dark vision but magical darkness can counter that so I could see (or rather not see) some potential there.

becoming the monster is actually something I've been wanting to do forever (ever since I played Fear and Hunger 2).

Really great ideas all around. Will definitely use most if not all of them, Thanks!