Board Thread:Questions and Answers/@comment-6496557-20130215014909/@comment-5790482-20130317200134

Look here: Legendary Dragon Breeding

Levels of your dragons don't matter, they just have to be over Level 4. If you use Breeding Boost you have higher chances, but you don't have to, I got Legendaries 4/7 tries without Breeding Boost, Soccer + Soccer.