Pillaging Van Richten's Guide to Ravenloft

 Any time a sourcebook comes out, I'm tempted to run some sort of adventure or campaign set within that world. But I also tend to prefer to run things in my own homebrew setting (I've put a lot of work into fleshing it out, and it's also custom-built for the kind of adventures I like to run). Yes, I'm currently running a Ravnica-based campaign, but I do feel drawn to return to my own mythos with all my own creations.

And then they drop a book like Van Richten's Guide to Ravenloft.

Ravenloft is a very cool setting, and has a truly unique feel to it, given its emphasis on horror. It's also very different from other settings in that it's not really a "real world" the way that Eberron or the Forgotten Realms are. It's an impressionistic land that operates on nightmare logic. Yes, it has inhabitants who are real people, but they have to navigate a world that is out to get them.

So, again, with any campaign setting book, I like to piece together what we as DMs (or players) can "pillage" from it - what elements we can take and use outside of a genuine Ravenloft campaign.

The first and most obvious parts are those that fit into D&D modular design. Van Richten's comes with two new subclasses (for Bards and Warlocks) as well as three new playable "races" (that can work a little differently than other races, but can also work on their own as well) and some backgrounds that could fit in other settings. These are all broad enough in scope that they could work in any world that has shadowy magical powers, undead creatures, spirits, hags, and the like. (In fact, I wonder if, should we get a Feywild sourcebook, we'll see the Hexblood reprinted there.)

Ravenloft's Dark Gifts have a clear source in the setting, but you could easily adapt them as an added bonus in other settings. These are mostly beneficial, and will likely be a net boon to your players' powers, but they all come with a downside that could make a bad situation much worse.

Moving on to other obvious things, the book has a decent bestiary which includes a number of deviously deadly monsters like the Dullahan, Jiangshi, Loup-Garou, Star Spawn Emissary, and the just-as-nasty-as-it-sounds "Zombie Clot." Supernatural terrors are not limited to horror-specific settings, and the Star Spawn Emissary in particular feels like it could be a recurring, mysterious threat in any campaign that involves Elder Evils, the Far Realm, or other aberration-type monsters as a major threat.

Organizations like the Priests of Osybus or the Ulmist Inquisition could easily serve as inspirations for factions in a homebrew world, and they have some unusual and interesting stat blocks to represent members. For instance, rather than having the Priests of Osybus tied to the Dark Powers, you could use something like them as any kind of powerful cult that employs necromancy in the name of just about any kind of evil villain.

Van Richten's has optional rules for Stress and Fear, which you could use in any game that wants to emphasize the toll that adventuring takes, and could work in any setting (I'm tempted to use them in addition to lingering injuries from the DMG in an actual Ravenloft game.)

Unfortunately, there's no big list of new spells (rare for a setting sourcebook) or magic items (conversely, usually pretty common in one) but I think we've actually got a pretty decent glut of such things in recent books (the items in Tasha's Cauldron of Everything are pretty extensive) so I actually appreciate the focus instead on making the elements of a game you're running matter more.

There's already guidance in the DMG on building villains, but you might look as well to the section in Van Richten's on building Darklords and the domains around them. While Ravenloft literally has the domains' forms determined by its Darklord, you can use the same guidelines for thematically linking a villain with the environment in which you fight them.

Even if not swallowed by the Mists, there's typically plenty of room for scary things in any D&D world. Some of the domains detailed in the book include outlines of the cycles of a plague, or how to run a zombie siege (which you could easily adapt as any other kind of siege. Maybe it's a horde of orcs rather than the shambling undead).

I'm on the fence, actually, between running a true Ravenloft campaign or just incorporating things into my own setting (I do know that when the characters in my Ravnica campaign eventually go to Innistrad, I'm going to be using the crap out of this book.) The guidance on building your own domains of dread is actually really great for us homebrewers, as it lets you build something that's entirely your own but can still interact easily with the rest of the canonical stuff.