Mass Driving
The technique of accelerating large masses (say a sizable asteroid) towards a planet. The resulting impact is usually exceptionally devastating.
All human polities have outlawed the practice against human-inhabited worlds under the Treaty of Geneva.
Originally this would have been done using a specialised Mass Driver Ship.
Mass driving was used extensively against the Exterminators. In the case of the attack on the huge Exterminator Base on Red Spot during Operation Gabriels Trumpet the asteroid impacts caused crustal cracking and massive x-ray energy emmissions.