Backup your item sets now!

We're currently not planning to bring over the item set creator feature from the legacy client. Basically only an incredibly tiny percentage of players ever used the feature, and we've heard from many players that y'all don't care whether we bring item sets over so long as we continue to support 3rd party item set customization tools like Championify—and we will!

http://euw.leagueoflegends.com/en/client-update/article/5900cc59-5e30-4a8b-acb8-9daf4c20d6c8