Dragon's Watch has Live Events - these change each day, week, or month. Live Events may be:
Summon Events - change the likelihood of getting certain Heroes via a Temple Summon. This can be useful if you want to strengthen your team in specific ways.
Dungeon Events - Limited-time Quests, which are only playable during the Event. Typically, Dungeon Events will have very special loot drops on completion.
Login Accumulator Events - Entering a Login Accumulator Event will give you new gifts every day you log into the game during the Event. Typically, these events last for 7, 14 or 30 days - and the gifts tend to get better with each consecutive day you play the game.