Story: Season 1

Chapter Mastery
Each chapter has a number of requirements to be completed in order to fully master it. These requirements are:
 * Quest Progress Task Icon.png Quests (Tasks)
 * Deploy Task Icon.png Deploy Mission
 * Heroic Battle Task Icon.png Heroic Battle
 * Challenge Mode Progress Task Icon.png Challenge Mode
 * [[File:epic ic.png]] Epic Boss

Mastering all the requirements yields various rewards for the player.

Mission Difficulty
Each mission, save the Premium Missions, has a set difficulty level. When a mission is 5-starred, the difficulty is scaled to the agent level the player is.

In Premium Missions, difficulty is set to the Watchtower level, no matter the mastery.

Challenge Mode sets the difficulty to to the Watchtower level +5, whatever the mastery.