I have a person who keeps attacking me and I can't get revenge because they never have any properties..

Delete them from your friend list. Someone constantly after you to get through all your shields to begin hitting your property is not a friend.

There is a way to block a person from being your friend. I did this last month. There was a person whom I did not add into my group of friends, had no idea who they were, but all of a sudden they were bombarding me. Since I did this, I have not seen or heard from the person. Click on FRIENDS (lower right), LEADERBOARD (right of 3 tabs), then FRIENDS (not global or local), scroll down to suspicious person, tap th FRIEND NAME, then tap on red REMOVE button. I hope this helps.