This is a plugin I'm developing for a friend's server (Which shall go unamed until said friend is ready to open it to the public) that adds the ability to spawn quill/books with a custom lore that identifies them as death notes to the server. They behave exactly as you'd expect, killing the player you write in the book after a delay specified and announcing the death as written.
It is currently incomplete, but the code is fairly easy to write, so the basic mechanics are almost done. Currently the only form of balance added to said death notes is that they are limited-use and become obsolete eventually. This plugin isn't meant to be very balanced at the moment, but later on I'll probably attempt to added other optional methods for nerfing the notes.