How to get lots of ISO-8?
I am level 44 and have completed 100% Story Quests Chapter 3. I have also completed a number of Event Quests both daily and monthly. Until recently I had only a few 4 star champs but now my 4 star roster has grown and I also have a couple of 5 star champs. But almost all of them are stuck at level 1 as I don't have enough ISO to upgrade them. I have upgraded 3-4 of them as much as possible and play with those in my AQs and AWs but I cannot start SQ Chapter 4 as it is getting difficult to complete any quest fully with the champs I have. How do I get a lots of ISO-8?