Server Maintenance occurs at irregaular intervals. There is no regularly scheduled maintenance or backup downtime, the maintanence is usually announced 1 to 6 hours ahead of time, on the game's Top Page, but some instances can be predicted.
Predictable Maintenance PeriodsEdit
Server maintenance will ALWAYS occur IMMEDIATELY (within seconds to a minute) after a ranking event is over, this is for the game develepers to remove all event page info, and essentially ensure the player ranks are locked in place. USUALLY the period is approximately 1 hour for large events and sometimes approximately 30 minutes for shorter events. Usually rewards are distributed to all players during this time so that the reawrds are in players' gift boxes once the maintenance period is complete, though some instances of delayed or mis-distributed rewards after maintenance end, have occured.
Server maintenance will sometimes occur immediately after a purchase event is over in order to prepare the pages/links to the next purchase event.
Unpredictable Maintenance PeriodsEdit
To prepare new events; exact launch times of upcoming event are usually vague with a "Coming Soon" Banner or no advanced warning whatsoever. Sometimes it occurs to prepare for release of new cards. In most cases an annoucemnet on the game's Top Page anywhere from 30 mins to 3 hours before the maintenance period is the only warning.
Major game system stability or bug issues may lead to unscheduled and sometimes unannounced maintenance. (i.e. Riot Rumble event exploit, Gargantuan Raid server overload).
If you launch the app when it is under maintenance you will see the image at the top right, clearing the popup will leave you with the current themed app loading image. You will need to close the app and relaunch it once the servers are active agin to login properly. If you were already in the game when it enters maintenance you will instead see the picture to the right. Once the game servers are back up you only need to tap the 'GO to TOP button to return the top game screen.