You can send your heroes to do different missions for you, where they have to fight different enemies. Each region has the same types of missions. There are five types of regular missions:
Additionally, every area also contains the following:
Depending on the type of regular mission, you receive different rewards that can be used in crafting. After completing a regular mission, the boss mission for this type can spawn. It stays for three hours and takes longer to complete than a normal mission.
You can send up to three heroes to a mission. Sending multiple heroes can help you when a single hero alone isn't strong enough to complete it. Your heroes will also gain experience for every successful mission which will increase their level. The gained experience is shared between the participating heroes.
If you can't beat a mission, you can try sending more heroes. You can also recruit a mercenary to help your heroes. They will take one of the three hero spots for a mission but do not receive experience. As they are relatively strong, this is a good way to assist weaker heroes.
Like your heroes, the enemies in a mission are also assigned a type according to the Rock-Paper-Scissors system. By selecting the right hero type, you can increase their effectiveness a lot. For example: if the enemy is a mage, you can send archers instead of melee fighters as they have damage and armor boosts against them. To further increase your chances of beating a mission, your heroes should wear the best equipment you can craft for them. Alchemist booster potions and guild buffs can also be of value.