User blog comment:Canopenerdude/Crazy Idea- ALL CHAMPION WEEK/@comment-24434281-20130508165356

Riot has only done a "All champion event" during that "Free Weekend" a few years ago, which if I remember was due to all the server problems.

Riot has no need to to host something like this, and have had no indication of doing something like it in the past.

I seriously doubt Rp or champion purchase will increase as a result.