What level were you when you defeated Damian's armada, after defeating Laiken in the Battle Tower? I defeated Laiken but cannot defeat the Armada, I die within a minute of play, not enough / strong enough potions left. I thought that once I defeated Laiken I would have a chance to get more potions, maybe level up before doing anything too grand. Instead, it the game throws you right into the Damian battle. I don't have a chance (level 17). Or do I?!
I think you need to practice more on aerial battle, how to steer you dragons and avoid attacks. You should at least had 1 free dragon skill point that time if you do pick up a dragon skill book before, which you can put into healing skill.
I will always destroy catapults 1st. Reason, they always had the highest attack range compare to those flying mobs, and catapults amounts usually outnumber those flying mob. Just make sure dont stop in an area for too long and you will have lesser chances of getting attack. Try to use your surrounding environment to benefits you, such as hiding behind some huge objects, rocks, hill and etc or even fly off the enemy attack range 1st if you found that you really cant take too much.