Board Thread:Support Requests - Designing Your Wikia/@comment-27004366-20150220012824/@comment-5558012-20150220014259

Some wikis use UserTags to implode (or combine) certain existing tags (such as Rollback, Chat Moderator, and Moderator combine to give a Mini-Admin tag) to create a new one. This is an easy way to create a new tag for users with multiple group tags without creating a new user rights group.

If you wish to actually create a completely new user rights group for the wiki, you need to Special:Contact Staff with your request including the name of the new group and the rights within it. I can't recall if Staff requires a community discussion before they will acknowledge these requests, but you might as well before sending one.