Level up your Heroes to increase their powers. Leveling up your heroes increases their stats (attack, health, and defense points) and maxing the level for Promotion.
A Hero can be leveled up by conducting the following:
1. Go to your Hero Roster by pressing the Roster icon at the bottom of your screen
2. Select a Hero from the Hero Roster
3. Press “Level Up”
4. Select the Heroes you wish to sacrifice to the selected Hero
5. Tap “Level Up”
Leveling Up a Hero requires sacrificing other Heroes (and a little food. Your heroes get hungry!).
The amount of Experience Points (XP) and food needed to Level Up the Hero is specified on the “Level Up” screen. You will gain slightly more experience if Heroes of the same color are sacrificed when Leveling Up.