I was looking at forums saying how if you build something then they would destroy buildings that you built. So i had some ideas that are: If they try to destroy say a message that says this block does not belong to you. Or a little pop up will pop up in the corner of your screen asking if you want to allow him/her to destroy your block. If you accept it you can go to the leader boards and decline the that player from destroying blocks. Comment on what you think of it!