Board Thread:Dragon City Questions and Answers/@comment-5995241-20130501190000

"You must have at least 15 Legendary Dragon Lv20, if you're manage them in good place, all of them can place on first island with about total 860%-880% Boost."

Sorry for my ignorance but I don't understand this, at this moment I can boost them up just 80%, why does it say to boos them up 860-880%? And how to do that?

Thanks in advance for your answers and help :D 