Proximity mines deployed to try to halt an opponent's advance.
 

 
Sometimes you've got to expand over bridges just to get energy.
 

 
A crawler runs into an undefended main hub.
 

 
A missile shooting down an enemy balloon.
 

 
If a damaged hub launches anything with a proximity mine that close it'll destroy itself.
 

 
A cluster bomb strikes a shield and some terrain.
 

 
A crawler follows.