Yo can now make the plugin work as a beautiful blacklist. And yea, it works also for groups.

You must delete your old config or add the missing values:

For spigot:
add use-as-blacklist: true under the settings section.

For waterfall:
add a settings section
add use-as-blacklist: true under the settings section
settings:
use-as-blacklist: true

Thanks to crashback for the suggestion

~Joey