Recommendation!

Ads are only activated when you click them for certain bonuses. While there are time-limited rewards and a lottery, there are also hidden missions with high rewards. If you remember to upgrade your troop types and attack power, the stages aren't difficult to clear, and you'll have more than enough resources. You can even play the game offline after starting it, and your progress will be fully saved without any loss (though there's no need to turn off your internet since there are no forced ads).