Chests are items in the game that contain collectable Cards. They come in three different tiers - Wooden, Golden, and Magical.
The Wooden chest contains 2 Cards, the Golden contains 4, and the Magical Chest contains 8.
Chests can be obtained in a number of different ways. While playing the game, you have the chance of digging up a chest during Raids, and finishing villages may reward you with a chest as well. On top of that, Chests can always be bought using Coins in the in-game Shop.