I see you really are contributing a lot to this wikia. I would like to contribute something but don't know where to start. I thought it might be a good idea to pass this on to an experienced contributor.
I've had some troubles remembering which heroes I could get to the next tier by creation circle. That's why I made an excel sheet with all the possible heroes you need for an upgrade so it would be more manageable. Let me know if you think this is useful. I've let my heroes in for reference so it's easier to understand. https://ufile.io/s2srh
p.s. I've made a screenshot of all heroes from 3 star so I think those would be useful on their own for this wikia.