League of Legends (LoL) Question: when will we be able to make item builds for champs again to be saved and a

IDK when they will add that back to the new client, but you can always use the legacy client (the old one, there's a button for it somewhere in the login screen) and make/edit your item builds there.

EDIT: Apparently, an Ask Riot post dedicated entirely to the topic of the client update was just released.

tl;dr: Use the legacy client to edit item sets for now. You should enter a game with a champion using the item set for it to be saved though (just enter a custom game then leave). Item sets doesn't seem to be an intended release function on the updated client though :/ so it'll be unavailable as soon as the legacy client becomes unavailable during March-June 2017. There'll probably be some backlash so hopefully the whole system will be back soon eventually.

EDIT2: A rioter said sometime before the end of Febraury that they'll try to bring back item sets to the new client. It'll probably take a while after the new client goes live, so we'll have a couple months of no item sets.

The new client wont have item sets, go into the legacy client to make your sets then they will appear in game while in the new client as well.

Jdjd