Board Thread:General Discussion/@comment-25512194-20150806152700/@comment-1038387-20150806153609

If the other wiki credits you (or your wiki) for the design, they're technically solid. "Permission" itself is not required, per Wikia's license, just attribution. If the wiki does not have attribution, contact the user and tell them to give proper attribution. You can also say you're not happy he/she took that design without asking first. They don't have to take it down if they credit you, no matter how much you don't like it.

If they won't comply, use Special:Contact/general.