It's a bit hard to see what's going on with the Black Holes though. A better show would be to crash two near-collapse stars together to trigger a supernova. As an added bonus you get a fresh supply of heavy elements, which your civilization might be running low on since your have the capability to fly stars around.
There goes my morning. I will be thinking about this for awhile...
I keep on thinking on how can we do it even with Super powers..