The old League of Legends client retired approximately a week ago, and one of the big complaints was the lack of item sets in the new client.
Item sets were a small part of the last client - through your profile, you could make up what was essentially your own custom “recommended items” page to show up in your game.
Riot originally stated very few players used this function so it was originally cut from the new client, but after some protest it’s been reinstated!
Item sets have been added to the Public Beta Environment’s client as of the 7.10 cycle.
It seems like the sets work similarly how to they did in the older client, but they just look way better! You also can now pick and choose what maps the item sets show up on, which is neato.
Item sets came back much faster that expected, so good for you, Riot!