Helped me not to much but it helped – GameHack: Guide for Clash of Royale Review

As you can see it helped me a little because I didn't know that you couldn't get gems from specific chests, And here's a tip when you're doing a challenge get the stronger spell so you have a high chance of winning you should also get cheap cards and a little bit of expensive cards
Review by grape/mom on GameHack: Guide for Clash of Royale.