[Heartless]

Actually I have two ideas in my mind. One would be an AJAX-like system where the page polls the server in a given time amount and updates some of its contents accordingly, and also to use something AJAX based for updating single calls - the page itself is performing pretty bad at most times.

The other would be to keep the defense page as it is and add "hidden" fields for the original call data, which gets compared to the data stored in the db after being submitted. This could then work like a lot of Wiki systems do: When a conflict is detected, it caches the wanted changes, shows the conflict to the user and then leaves it to him to either proceed or cancel.

From a quick guess the first solution would be superior from user-experience, while the second seems easier to implement I guess.