Make sure your heroes are fully upgraded, especially when you have problems with a certain level. Every hero has a weapon and armor that can be upgraded after spending coins. They also give active and passive skills, but these must first be unlocked by spending scrolls. Scrolls are obtained by completing a level without losing any lotus leaves. Spend coins to upgrade allies to improve their attack damage, health, and blue orb cost. Allies can also evolve after they reach their maximum level as long as you have the required resources.