A WikiTroll is a person who purposefully defaces a document on a wiki. There are a few methods in place for dealing with WikiTrolls.
How to revert a page
Any page can be reverted to a previous version. Here's how:
Simply click "history" at the top of the page you wish to roll back. Then click on the time and date of the archived version you want to revert back to. The page will appear with the version indicated at the top of the page, just underneath the page title. Next, click "edit" at the top of the page. Add a note in the Summary box that you are reverting the page because of a troll, and then click "Save page".
After repeated defacings, an offender's IP address can be blocked by several users who have sysop rights. These admins pay careful attention to the recent changes page, and will block IP addresses where/when appropriate.