Personally, I love my 2* collection. I thought the 2* only arena (for a 5*) a while back was a great way to keep them part of the game. Now that 5*'s are so much more common, is there any consideration for making that a monthly (or every other month). I believe that would be a worthwhile recurring event.
Along those same lines, as a long time summoner, I find my 4* collection not getting used near as much now. Any ideas on ways to keep using them? I only find myself using them for the monthly event for Master level. I use a few for sector 6 incursions. Any thoughts?
Oh, and don't bother bringing up 3*'s. They are dead to me...