I made a Jester and Jongleur subclass for my homebrew.
Some of the kits would probably just be a background - Charlatan, for sure - maybe Gypsy-bard (Outlander? background) and Herald (Criminal/Spy background) and Meistersinger (Entertainer background) as well.
Blade I think is College of...
There was a 3.5 book Elder Evils, that I believe had some Cthulhu-isk beings within. I don't think any of them ever grabbed anybody in a way they lasted beyond that book's printing.
But I don't mind straight up Cthulhu and his ilk showing up in a Ravenloft book. We've had variations of the...
Not all Thayians are bald, tatooed wizards ...
and...
(In fact, as I remember, the first bald, tattooed Red Wizard I remember was Hazlik, who as punishment had his head shaved and tattooed with woman's tattoos - only women tattoed their head.)
...And to one up that one, an adventure set across domains, where one of the PCs is a cursed werewolf from Kartakass who runs around with a group of troubleshooters unveiling minor would-be dark lords...
"I would have gotten away with it too, if it weren't for you meddling kids!"
Sounds like an adventure to set within Hazlan, with a pseudo (shadow) Zass Tam to show up to irritate ol' Hazlik until the dark lord can trick some young students at the Thayian Academy to do his dirty work and eliminate the lich lord. :D
I suspect that is Strahd's hand on his shoulder, ala Where Black Roses Bloom.
As for "season of Champions", we did get a pugilist class, so my bet is on a book for the "martials" akin to the spellcaster's book of Arcana Unleashed. It just doesn't feel like the right title to associate with...
I've taken to referring to it as 5e14 and 5e24, as I'm somewhat expecting we'll see a 5e29/30 (and at that time 5e14 content will be fully retired from Beyond).
I'm still using 5e14, BTW, with no plans to change - but I'm still watching for 5e24 books that catch my eye (like the recent Eberron...
There is also Masque of the Red Death - it is considered to be a "domain", and actually has Frankenstein and Dracula in it. There's even a version available on DM's Guild for 5E.
On Cthulhu, if anything I would have considered him one of the Dark Powers themselves, not a Dark Lord. We have...