In February, Google launched campaign drafts and experiments for AdWords and then also pushed it out for display ads. Well, it didn't last long, Google is discontinuing the feature in the upcoming months.
Google quietly announced on Google+ that no one will be able to make new Campaign Experiments starting on October 17th, 2016. Plus, any active campaign experiments will "automatically end and all unapplied experimental changes will be removed," on February 1st, 2017.
Google recommends you end the campaign experiments yourself before this deadline but if you don't, Google will end them for you.
Forum discussion at Google+.