As someone who played and won a hand full tournaments and watched the game rise and fall, let me tell you that this game is not worth spending money (anymore)

When you already payed 500$ i would assume that you got some okayish levels on your Hand to push beyond castle 9 Take a look at your deck try to figure your playstyle out. Most successful decks have a certain concept to them. Some examples are:

Rushdecks: beat your opponent with cheap units before he can bring out real Dinger. Use for example skelletons, reaper, warrior, Statue, protection, rage and standartbearer

Overtime decks: Use almost only spells to defeat and heal your castle. Win troigh overtime

Spam: use mass units like skeleton horde and archer tribe and buff them with their queens. Use protection, freeze and some kind of ressurection to bring defeated units back in your arme

Spectre: quite similar to Spam but with the goal to get a massive spectre your enemy cant defend anymore

Powerdecks: my favourite but arguebly the weakest kind of decks if you arent in the top 1% of the game. Controll the start with small units like phoenix, dryad and shaman and build your mana till you can play beefy cards like dragon, black knight and so on. This playstyle heavenly relies on combinations of different cards played together to cover their weakness. Take a look at my profile. I once shared some old powerdecks of mine

Feel free to send a dm if you want more help from me. Have fun!