The Mystery Box appears in the players Turf with a countdown just below it. The countdown lasts for 1 to 60 minutes. Open the Mystery Box when the countdown ends to claim a random reward. After a certain number of boxes have been opened, 5x rewards will be given. There are some Guild Fest Quests where a number of Mystery Boxes must be opened within a given time.
Battle Fury • Buildings • Castle Skin • Familiars • Mystery Box • Pact Case • Research • Shield • Shops