Well, I just hover at the top, and when I can, I dive down at a nest, shoot a firewall, and duck back up again. Usually, there will be Memory Eaters around 2 bottom nests, so put on a Shield, heal before diving in, or summon a creature to aid you before you dive in. Eventually, they will all be destroyed, and you will have to fly into a black orb at the end of that area.
Then you will reach a long path, and after going through the path, you will be in an arena, and will have to face 6 rounds of bosses you've battled before. They are (in this order):
Marius & Gene
Evil Sassan
Amdusias
Laiken & Razakel
Lord John & Lady Kara
Ba'al
And after that, will be the Final Battle, the fight of your life.
