This explains in some detail the battle mechanics.
As for defenders item and assign, item comes first and then spell I think.
and a flying red played by Thaliongor. I was sitting at my pc taking a look at my account, when I saw Thal going down, and I was the only available target, so I was sure he was going to hit me. I was also sure he was not going to win, as he already tried countless time but never succeeded, cause my stack was pretty solid and I had some good heroes left, while he was not heroed up at all. So, he attacks me and lose. And I think that if I online counter him is some nice free land for me

Though I have to say, I didn't know there were a sort of "gentlemen agreement" between him and P, not to play too hard, and he had respected that. But, since I didn't know that, I online countered him and won. And, don't ask me why, but I was pretty sure he was going to swing

So, you see, I exactly knew what kind of enemy I was going to face, in a few minutes, time for him to power up hard. A flying red. And then, from the assigns carpet/levi, I changed in order to adapt to him... Between, Lucis, who said that levi is not that useful against all flying?

Put dust/levi as assigns and start to laugh hard!!

As you can understand, he failed to grab me from something like 10-15 millions above. Not that even 150 millions would have made the difference, lol.