You will fight against enemies by consuming "Stamina" and you will get either an Original or Replica Sphere by winning the battle.
You can see the type of enemy that you would encounter as well as the possible item drops before you challenge the quest. It is recommended to plan your strategies ahead if you’re having difficulties beating a quest. Take into account the type of enemies you’ll be facing, and don’t forget about elemental advantages.
Your Brave Burst usage will be reset for each battle.
Additionally, you will get experience points (EXP) by beating the quest (only surviving units). The amount of acquired EXP will be different depending on the difficulty. Level up your units quickly so you can try out higher-difficulty quests as soon as possible!
Spheres won't get EXP from quests. You can only level your Original Spheres up via Composition (Sphere Fusion) using your replicas.
Higher difficulty quest means greater chances to obtain better Spheres. It is recommended to level up as quickly as possible so you can give high difficulty quests a try!