What is the Mission Portal?
The Mission Portal provides your heroes with a place to train and earn XP and other rewards in the background. Missions cost Gold to complete. There are a number of mission "slots" you can unlock as your level up your town. Later in the game, you can have several ongoing missions for all of your unused heroes in the background. You need at least three heroes to start a mission.
Who can go on a mission?
You cannot put heroes in a mission if they are currently part of your adventure team.
You can put heroes who are on your PvP team on a mission, but you will not be able to change their weapons in PvP if they are on a mission. You also cannot add a hero who is currently on a mission to your PvP team.
What does mission difficulty mean?
The mission difficulty indicates how difficult it will be to get bonus rewards. You will always get XP rewards for a mission.
Easier missions give less rewards, but they are easier to win.
Harder missions grant more/better rewards, but they are harder to win.
For example, to win the bonus rewards for a very hard mission, you must pay attention to buffs.
What are buffs?
If you equip weapons of the right type and element to heroes of the right element, you increase your chances of successfully completing the mission.
Here is an example of a mission you can go on.
It will take 1 minute to complete, and when it's finished, the heroes who you sent will earn 5% of the total XP needed to reach the next level. It's a "Normal" mission, which means it is average difficulty. This mission has no buffs.
The Illusionist, Demon, and Necromancer cannot go on this mission because they are currently part of the player's adventure team.
The bonus chance is 100%, which means it is guaranteed that if you successfully complete the mission, you will get the bonus rewards. These rewards are bonus in addition to the XP the selected heroes will gain. Note that in the above example, the Empress will NOT gain +5% XP because she has reached the max level she can before upgrading.
What happens after I start a mission?
If you want to see what's happening with your mission, simply click on the missions portal to view how much time is left. You can finish instantly with Rubies or abort the mission if you do not want to wait. Note that by aborting you will lose the Gold you spent for the mission and your heroes will not receive any rewards.
If you hover over the "i" symbol, you can see which heroes are on that mission and what the awards are.
What happens if I skip a mission?
If you skip a mission, you will have to wait for a new mission to appear in that mission slot.