From Dragon Mania Legends Wiki
In Dragon Mania Legends, the main story is contained in a series of Campaign Quests, spread across various islands occupied by enemies, for the Trainer to complete to free Dragolandia. There are 5 types of quests: Main Quests, Boss Quests, Side Quests, Rusty Gates and mines. The Campaign Map can be played in two different modes, namely Normal Mode and Heroic Mode, and is accessed through the button in the bottom-left corner of the screen or by selecting the Ancient Portal and pressing the same button. The Normal Mode can be played since the very beginning of the game while the Heroic Mode is unlocked once the Trainer reconquers the third island of the first mode. The Trainer can toggle between the modes using while in Normal Mode and while in Heroic Mode. Additionally, whenever the Main Quest that is currently available to battle is out of or almost out of the Trainer's visual range, the button will appear in the left-hand part of the screen and pressing it will take the Trainer to that quest.
See Clockwork Dungeon for more information
The Clockwork Dungeon is a place that can be accessed from either of the modes and has six quests for the Trainer to complete each day. It is unlocked upon reaching Level 16. Unlike most battles on the Campaign Map, all Dungeon Quests feature 2 waves of three Dragons that a Trainer must fight, for a total of 6 Dragons fought per quest.
Each battle on the Campaign Map takes place in various battle scenes, depending on the quest and island. The scenes in Heroic Mode, although the same as those in Normal Mode, are slightly darker in tone.