So, Duel-a-thon is a nice "event", I hope it becomes permanent, although I doubt they're willing to give 60 gems for free everyday (although I don't see any problem with that, to be honest).
I haven't seen the new Booster, but from what I've heard, it introduces several cards that are sure to reshape the meta.
I agree, really like this kinda-event. Gives a reason to play at least, and free gems= free gems