Spammers will be blocked and bombed.
How to roll back a page to a previous version
A quick way is to open the Mediawiki History page showing the list of page edits, find the article version you want to revert back to, select Edit and then Save.
The newer versions are permanently deleted, only the chronology is left, which means you cannot change your mind. However, I found this option perfect for getting rid of spammer inserts, when there is no reason why I should ever want to see the unwanted information again.