Firstly which one is correct? The Blackbox edition mentions tearing down buildings of each opponent but the IV edition doesn't make mention of this at all.
Also, it says to tear down 'matching incomplete building'. What is it matching?
Matching the colour of the legionary card lead? Matching the building type on the legionary card lead? Matching the colour or building type of the card you are wishing to steal with the legionary?
If someone is able to clear this up (or point me to somewhere this has already been discussed) I would be grateful.
Matching means matching the colour of the material you wishing to steal with the legionary.
My assumption is that you do this once per opponent that you are targeting with the legionary. If you have a card which allows you to target all opponents then this should work on them too.
Edit: Here is a link to the official clarification.
Re: Playtesting needed for official GtR mini-expansion/variant