I have an ongoing border dispute with next door
and his plans to build a large extension,
encroaching invasively onto our back yard and shared alley...

So It's ok for me to lob a brick over the fence at him and his architect as a warning strike...???

You're making no sense, try this:

Your neighbour is trying to break down your fence in order to gain access to your property with the intention of killing you. Do you have the right to defend yourself?