My son and I were thinking....

Perhaps an ability to crash capital ships into planets would be a fun ability to have... destroy the entire planet's surface with the impact of one or two capital ships, leaving the surface radiated for a few minutes.  Be a nice trick to use........ picture with me, if you will, a capital ship that, once it uses the ability, bursts into flames.  The player then does his best to kill said capital ship before it finishes it's headlong dash insystem to slam into the planet with an epic crash!!!!

Or,....  detonate a Titan above a planet and it takes out the planet with the shockwave shutting down all defenders and orbital platforms for a few miinutes.