Namor, Black Panther, and Dr. Doom versus Marvel Earth
The 3 rulers meet secretly and agree to work together to take control of the world. They want to expand their respective kingdoms, with Black Panther taking control of Africa and Western Europe, Doom taking control of Asia and Eastern Europe, and Namor taking control of the Americas and all the world's oceans. They have one month of prep to coordinate an attack on the rest of the world...can they succeed, or will they be stopped by the world's governments and superheros?
Now in all seriousness, Namor and Doom spend their free time trying to invade the world and they always fail. Why would they succeed this time? A cosmic arm-bar?