From Brave Nine Wiki

Quests are a series of missions given to the player to progress through. Most of the missions involve completing Campaign mode stages, although other quests (eg. Summon) do exist as well.

The rewards given include Diamonds, scrolls, Runes with high Star Rank, Skill Books, Ancient Coins, and other valuable materials.

There are currently 242 quests in total - 202 for Campaign Part I and 40 for Campaign Part II.