If you have Pass Royale you can queue a Chest which means as you unlock a Chest you can set on another to start unlocking soon after the current Chest finishes unlocking.
Unlocking a new Arena adds new Cards to the Chest rewards - none are taken out. Chests always contain cards from the Arena the player earned them in and below and/or cards the player has already unlocked, except for Legendary Chests, which can contain a Legendary Card from any Arena. It is still possible to battle when your chest slots are full, but no chests will be won, only Gold and Crowns.
Each player has four chest slots, so you can only have up to four chests waiting at a time. Alternatively, the wait can be skipped using Gems/Chest Key or hastened using boosters upon reaching a new Arena or League. Unlocking a chest takes a certain amount of time. Chests are won from battles and must be unlocked before you can receive their contents.
You can earn Chests to obtain Gold, Gems, Cards, and Wild Cards.
