D&D 5E CoS Castle Endgame Crazy Stuff

[DEFCON 1]

So both of my Curse of Strahd campaigns are ending, with each of them having probably two sessions left. Both groups are about to enter Castle Ravenloft for the last time to take on Strahd and his minions. However, rather than just a combat slog through wave after wave of minions and undead... I'd like to add in some "flavor" events or encounters throughout the castle that aren't strictly combat-related. I have a couple but I freely admit that creating this kind of really interesting weirdness is not something I'm good at as a DM. So I'm hoping some of you might have some cool ideas of "things" (scary/sick/otherwise) that the party might come across or experience while traversing the castle as they go to the various rooms in preparation for confronting Strahd himself.

Some things I've already got on my list:

- a trail of corpses each with a different missing body part throughout a section of the castle
- a tidal wave of Crawling Claws to overwhelm someone
- clouds of mist that make someone hallucinate (perhaps the castle rotating/changing Inception style)
- Rahadin's 'Deathly Choir' is heard even though no one can see him

Any other cool ideas that people are willing to share? Much appreciated!

 

[Ganymede81]

A wandering veiled bride. If they lift her veil, it reveals a skull instead of a face. She then collapses into a pile of bones and rotted cloth.

 

[Ganymede81]

Pildwick II is already a weird encounter. Maybe you can move that encounter to a place more easily accessible in the castle.

 

[UnknownDyson]

Have Strahd approach the most blood thirsty, ambitious or "evil" party member (alone, the dream spell or some sort of shadow demiplane enveloping the player would be good for this) offering either the gift of vampirism or some sort of boon in exchange for the player character assisting strahd in faking his death in the final confrontation to throw the party off his trail and out of his plane. Effectively Strahd would use the player character like a contingency plan, have everything play out normally but if the player characters aren't able to discern what's up, Strahd pulls some trick with the player that allows him to go through some fake but very convincing death throws.

 

[Quickleaf]

Ossuary of skulls from past minor villains the PCs have killed or NPCs who died on their watch. The skulls can talk and are universally scornful and deceptive, but may know a secret or two worth learning.