Chests are prize packages containing stable currencies and randomly assigned sets of cards that players can earn by winning matches or purchase for fixed currency. What cards are in a chest are hidden from players until players buy and open the chest, revealing its contents. Chests only contain cards that are currently unlocked for the player. Unlocking cards requires reaching certain Levels (see Troops and Tactics).
Opening chests obtained from matches requires a certain amount of time. The rarer or more valuable the chest is, the longer it takes to open it. Once the chest timer counts down, the chest can be opened, but the player has to manually open the chest by tapping the 'open' button for that chest.
Each player has four chest slots filled with chests earned as match rewards. Therefore, up to four chests can be stored at a time and only one chest can be opened at a time. Any chest can be opened instantly by spending cash from any chest slot (including chests currently in the process of opening). The cost of opening a chest with cash immediately depends on the time remaining on the timer of the chest. Store-bought chests do not fill chest slots, instead they open immediately.