I thought level 11 puzzles would be easy, so I jumped in, but...

It seems like you need to clear about 200 rounds to beat level 11. The difficulty isn't too bad up to level 9, but from level 10-11, there are more card types and hidden tricks, which can be quite annoying. However, the game gives out items frequently, and their performance is decent, so if you can endure the grind, it's not too difficult to clear. As for ads, I've set up a DNS block to prevent them... Short ads might still slip through, but since they don't pop up mid-game, it's bearable. Seriously, 200 rounds is incredibly tedious. Wishing you all good luck! ㅎㅎ