And to get a complete 3 stars on stages just requires luck since you just kills all the bosses on easy. On helll difficulty you'll have more chance since the enemies just have extremely high hp. The way you're supposed to do it is by using a button that requires some silver on the bottom right if your screen, but if you use the mega mod, it will show up a prompt saying that your account is being logged in from another device. Therefore, like i said, the only way to get 3 stars on stages is through sheer luck. For combos you just use the auto attack button and hope for the best, and as for HIT, especially 4 or above, requires you to actually combine 4 pair of cards at the same time.
Hope this helps you out.
