If I was going to destroy the world, Requiem for a Dream.
As I stood on the deck of my warship, high above the cities as my bombers laid waste to them in a purging inferno.
If I wanted to take over the world, Step in time from Mary Poppins.
Dick van Dyke leads my army through the cities, turning everyone into dancing chimneysweeps as I follow with Julie Andrews by my side, practically perfect in every way.
...Thankfully I'm more of a good guy in real life, but just in case, if you hear either of those songs playing off in the distance, take cover.