I've always tried not to mention their names, or give them any attention if I can help it. Granted I am human and have made my own mistakes with trolls in the past. The less attention you give them the more you win. Sometimes you have to call them out, some things you can't just let slide. But still if you have to do that then simply return to ignoring them, let them yell at the empty reply space because they aren't worth the time.
