Well, here's what I did.
It was sorta a hit and run strategy. Just hover over the entire field, as high as you can go, go past a nest tower, and hit it with a fireball. Duck up again, fly to the next one, and use fireball on that one, then duck up again. And repeat til all four are dead. I had 1000+ health when it was over. And, if you find a time when they are swarming on you, use the Summon Friend one. Also, if you want to get a nest that is surrounded by Memory Eaters, it'd be wise to put on a dragon sheild and heal before you rush in.
Hope this helps!
