You get one free chest with cards and elixirs every 4 hours, and if you’re lucky - it might be an iron chest with rare cards. So don’t forget to check the store regularly! You can get more chests by watching an ad.

 

You can double the income from your shafts and forge for 3 hours by watching a small ad. To do that - tap on the “boost” button at the left of your main mine screen.