Confirmed. I went in recklessly. Relied too much on the birds. Also, I played the fight poorly. I should have cleared one more Griffin Conservatory first - that's actually where I was heading
And I picked up a secondary along the way - a mistake.
After that I ran around looking for artifacts and Dragon Fly Hives and found nothing.
In the end I had 20 Wyverns, 6 Angels, and 5 birds.
5 Black Dragons from the opponent and the rest miscellaneous. But the main thing - the spellbook (Slow, Weakness, etc.)