Classic pay to win scheme. Quickly get out powered that you either grind the same level for days, or drop cash. Even the bonuses from watching ads only help so much. This is just a grind. And the cherry on top, is that this game blatantly rips off kingdom rush, a significantly better game series. From the art style, to the hero's, even the name. Advise avoiding and playing a game with some unique identity and soul.