1: Troll them even harder. Trolls are usually people who are just projecting pent up anger issues at other people and they'll always choose the easiest target to hit. Like Justin Bieber. Usually they'll determine this based on any material you create and attack that, seeing as how, unless you make it public, they know nothing else about you and that you're probably sensitive about your work.
Try to ridicule them on the grounds that they're losers and if that's not extreme enough well, you might have to become a real asshole and poke around to bush to find abuse issues.
2: Block them. This is the verbal equivalency to that of smushing your own shit in their face. If they create alt accounts to call you a coward for it, reply with "wow you're a loser" and block them immediately after. This will piss them off more than anything in the world and will eventually get rid of them.
3: Never reply to them at all. You'll become immediately boring to them and they'll find someone else to troll.
4: If the user creates multiple alt accounts, contact an admin and let them know that they're breaking the rules while listing all the alt accounts they've been using.
