I have been playing this game for a while, and I thoroughly enjoy it, I have a few minor gripes.
Exploration seems a bit over tuned? For example: The exploration mission claims that you need 3700 in power. I couldn't defeat it when I was 300 points higher. It took me until I was roughly a thousand points higher than the mission to be able to defeat it. (I've noticed the same difficulty at lower levels as well. Despite like 100 points higher than said mission, it's not possible to defeat it) Breeding chance percentage. So, I've been trying for quite a while (Maybe a minimum of three weeks and back to back at that) to obtain a duplicate dragon (4*) in order to keep training. And I have yet to acquire the duplicate despite using the 4* dragon and a 3* dragon that only gives me three results. I understand needing a low chance to ensure grinding and whatnot, but needless to say, it's a bit aggravating. Maybe even in need of a little fine-tuning? It's not only the duplicates giving me difficulty, but obtaining 1* star dragons from cross-breeding to help finish collections.
Anyway, those are my gripes. Otherwise, as I’ve said, enjoy the game and intend to keep playing.