How to deal with trolls here?  If it were me, I'd give a warning for each instance of obvious trolling.  3 warnings = a ban.  They can write up a ban appeal to possibly get unbanned if they want, and the moderators would review it and vote on whether they believe the person would correct their behavior and should be given a second chance.

Thanks for pointing out that I need more information for my own forum's procedures for dealing with rule breakers.  That should definitely be specified, at least to some extent.  I imagine the procedure will end up similarly to what I just stated above.