Players can access the map option in campaign mode, and choose different maps to fight on. Players can only access three maps in the beginning. You can only unlock advanced maps when you upgrade to the silver or gold level of your current class.
Guides
The Treasure of the Dragon – Beginners Guide
Beginners Guide Campaign: enter the map selection interface. Currently, there are 6 maps for players to choose. With regard to map selection: All bronze classes only correspond to three primary maps. […]