You're absolutely right
And this can be a nice asset to your well-being.
However, a note of caution to the other players. The adventure spells (or whatever they will be called in english) have limited use. This means they're best used in battles with bosses and castle sieges. In addition to that, if you're striving for a faster victory, you don't always have the luxury of going back and forward between the continents to add the extra troops.