Location: "Actions" menu
The "Prevent author from posting" effect enables you to block a user for a certain time, keeping them out of an opportunity to post comments.
To apply this effect you should open the "Actions" menu, located under the comment of the user you want to block, and click on the "Prevent author from posting" icon:
Set the duration of the effect and after that click on the "Apply for X points" button.
Note: This is a "paid" effect which means that you’ll have to spend a certain amount of your points to prevent authors from posting comments.