So far this adds two buttons and a buggy dropdown menu (with nothing in it). You can currently block stories forever and authors forever.

Plans:

• Unblock last author control
• Unblock last story control
• Unblock all stories
• Unblock all authors
• Unblock author by id
• Unblock story by id
• Export blocked authors to file
• Export blocked stories to file
• Import blocked authors from file
• Import blocked stories from file
• More stuff after I complete basic functionality

Here's a picture of how it currently looks:

For the record I use Stylus (chrome|firefox) & this theme