https://www.spigotmc.org/resources/oh-the-dungeons-youll-go.76437/
This generates dungeons, or allows an OP to generate them, and you can configure the loot and types of dungeons and it's a really cool challenge for players in general, on say, a survival server.
This could enhance the gameplay of vanilla+ servers because it's a really configurable mod that allows you to customize spawn rates, loot, which mobs spawn, etc.
Thank you for your time, I know i've been making a lot of plugin requests but I hope I can see them added soon.