Offline Gains are earned when you are disconnected from the game for any period of time. Only 90% of the time the player is offline for is exchanged to offline gains, with a maximum of up to 14 hours.

Offline Gains

Message displayed when returning from being offline

Offline gains reward Gold, and Experience, and Cards only.

Example: If you are offline for 10 hours, you will earn a bonus as if you were online for 9 hours (90% gain), so long as your total rest time does not exceed 14 hours. This is excluding the party bonus lost when offline.