There are different kinds of quests, all differ by duration, and all have different reward rate. The longer durability, the less reward rate it will have, and the more time dragon will need to recover. Therefore the you should is motivated to play the game more often and to manage quests smarter.
Player can do 5 quests simultaneously, while they may differ by duration.
Reward is determined as the dragon’s rarity times the quest duration times the reward rate.
Besides getting mana potions, player can get talisman shard and\or talisman recipe.