FREE to Watch (not to own) for a limited time, among the latest CreativeLive FREE to Watch Online Classes is an introduction to using Multiple Flashes by Mike Hagen. An artful science some could argue.
Judging by the schedule over there, the class will repeat until 9am pacific on Friday 9/15/17. The class consists of 27 video lessons. It is free to watch during this promotional period. If you want to it after that, you have to either purchase it (on sale for $39 during this promotion), or wait if/until it runs for free again as part of another re-airing promotion.