Grats Myrdin, I haven't managed to pull a second rainbow yet but I'm doing decently okay with gold pulls.
I now have a total of 18 golds (including 2 events and my starter gold) and 1 rainbow.

I think the game is intended to be grindy because the maps/stages are really short compared to FKG. You can blow lots and lots of stamina in a really small time frame.