What is the trick to this game peak of combat for mobile

Seems like Im not understanding how to get better cards and unlock more characters or something cause I grind and grind but get nowhere what's the trick guys?

I'm afraid there isn't one. It's straightforward. Pay to win. The game has gotten a lot of fire for its practices and there is no way around it. What you see is what you get. You can youtube everything you need from the game, tip, tricks or coverage of the situation for more details on everything.

It’s all Automated, roll to get your favorite character and just max upgrade them and sit back and relax