You can use Legendary Fisherman deck, some people have shared their deck before which work very well for me, combined with either GK Vassal or Catapult Turtle.
The problem is I don't have most of the necessary cards for the decks. Like I don't have catapult turtle. I don't have the gravekeeper black cat yet because I only have Ishtar at level 15. I also just would like someone to point me in the right direction on what to do to improve my account, like what characters to level up and what mini boxes I should be opening.
All these top decks everyone is using requires like having 3 of the same ultra rare cards when I'm lucky if I have 1 of that specific ultra rare. Id be willing to share photos of the cards I have if anyone is willing to help. If you're serious about helping email me @ irishwhiskey101@gmail.com and ill reply with screenshots of my cards. I can never beat level 30 consistently, let alone lvl 40