Not evilest (genocides, infanticide, and the like are no fun to read or to think about), but toughest, strongest, most dominant. How do you become the Doctor Doom Supreme of this universe?
You don’t have to explain how you accomplish your task, just what you would do.
Fun answers encouraged; don’t be a bummer. (marking NSFW just in case to make mod’s lives easier)
I would create a factory system for growing human babies that gave off pollution that made people sterile.
That sounds a pretty neat optimisation of the birth giving process. Might even solve some countries demographic issues!