DNA3000 wrote: » I'm not sure if this is a useful answer, but I've found that the best source of ISO is duping champions, and that means the most plentiful source of ISO is arena grinding for champions and crystal fragments. That might not be helpful to non-arena grinders, but for those that do at all specifically making it a point to reach milestones and even acquiring the featured 3* (since it doesn't take much work) can as you start duping champions regularly create a steady stream of ISO. I find I make no attempt to specifically do anything to get ISO, and I'm constantly selling expiring ISO. I'm pretty sure that's because constant duping of everything from 2* champs to 4* champs creates a large enough supply to mostly moot the problem.