Battle in the blink of an eye
If you are on the defense, your job is to try to stop the opposing force from taking the fortress guardian down. I know a lot of people have complained that there is not much strategy involved, but all I can say is that I had crap-ton of fun while both attacking and defending said forts. Watch out for the Jade Dynasty Gold though, because they love to make an entrance during these battles and can turn the tide of any given battle in the blink of an eye.