if you where able to summon anything what would it be?

[Inichi Matsuka]

It's scientifically impossible for a dragon to breathe fire and fly.

Not true; it's possible they had helium somewhere in their bodies. Since dragons were supposedly so large, it's natural to think they'd be too heavy to fly. However, since helium is very lightweight, they could have been able to. It's also a possibility that their lungs contained hydrogen, with some kind of dietary reason as to how they could withstand breathing fire. I saw a documentary on it a few years back; ugh, I wish I remembered what it was called.