Trying to determine what to say to disruptive community members can sometimes cause the worst cases of writer's block. You want to be an enforcer, but you also want to be a friendly face they can come to with help. Here are four sample snippits that can help start you on the road to a well-written response to a troll.
Have a set of community guidelines. Guidelines give you something to point to when you need to handle a disturbance and, if well-enforced, give you backup when members find themselves on the wrong end of the community law. When you see a troll wreaking havoc or members reacting to a troll defensively, speak up and remind everyone of the guidelines and what action you might need to take soon.
"While we definitely encourage members to share their opinions, the first rule in our community guidelines is to Play Nice. You can have differing opinions without resorting to name calling. I know we all want to get back on topic, so let's bring this to a civil place. If the discussion continues to get out of hand, this thread will be shut down."
Have some empathy. Is the person you're dealing with really a troll? Or are they just not getting it? If you think you can turn your troll into a productive member of the community, reach out to them. For example, I once had a community member that was contributing to wiki pages by deleting all the existing text then copying and pasting text from Wikipedia. It wasn't a malicious action, he was just a kid and didn't understand why that wasn't okay. A few emails turned what could have become a rage-react scenario (if I'd just cut him off without communicating) into a teaching opportunity that ultimately produced a more conscientious community member.
"Hi, I noticed that you've been having some trouble with editing pages. While your contributions are appreciated, it's not really kosher to just copy what other people created. Nor do members appreciate it when you delete their hard work. A better way to make edits would be to pick a small section of a page and do some research on it yourself. Quote Wikipedia or other websites where appropriate, but make sure most of the language is coming from you. It'll sound better that way, too. If you have any questions, let me know!"
Keep an eye on self-promoters. A community member who comes in and diverts all discussions back to themselves can be the biggest turn-off to a community. You don't want to react too quickly, though, because self-promoters can be turned around. It's up to your discretion (and your community guidelines) as to whether you delete the offending post, but whatever course you take, a private message should follow.
"Thanks for your contribution and welcome to the community. Your blog looks great, but to keep discussions on track and topic here, we have a no self-promotion policy. If it's relevant to the topic at hand, feel free to share a link to a specific post or other piece of content, but off-topic posts that are just links to your blog will be deleted."
Be transparent. When a troll is set on creating drama within the community, you want to make sure that the consequences you hand out don't create more drama themselves. If you have to ban someone after a high-profile blowup, make sure that your reasons for doing so are clear.
"UserA was a valued member of our community for a long time, but after the recent incident, had to be banned from the community. We tried to work with UserA to address their concerns and problems, but no solution could be reached and UserA became too disruptive to the community. We understand that many of you may be upset about this and welcome you to share your feelings in a manner consistant with our community guidelines, but this decision will not be changed."