Unlock All Champions in Customs

We get it, we'll never get a sandbox but the game is lacking a way for new players to truly explore the game. I've made a few accounts to play with friends that are new to the game and almost always I stutter when they ask who they should play because I don't even enjoy any of the champs for that weeks rotation. At least give them a chance to test out champions, to find that one or ten that they want to run with and get hooked to throw money at you like the dirty whore you are.