Content and hero progression idea

I would like to see a match style mini Game that allows the progression of 4* hero’s to become more like 4.5* hero’s with stat progression closer to current 5* hero’s.

In other words it allows players to progress thier 4* hero’s stats only thier special stays the same. I don’t think there is a single 4* hero that this type of progression would be unbalanced as even strong hero’s like kashrek would still be weaker then an equivalent 5* like Guinevere but allows more casual f2p players a way to progress in events easier.

The idea of tying this to a gem game instead of normal crafting or item progression is to add some side content. Especially if it’s more of the classic gems game style.