Ultron vs. the Destroyer.
Hank Pyms ultimate admantium creation believes he can evolve to a technomagical god if he could only get his hands on Odin's mystical creation. However the Destroyer is currently embodied by Lex Luthor, and should the Destroyer be defeated, Luthor dies. However if Luthor wins, he gets full access to both the Destroyer suit and Ultrons... corpse
They fight in the middle of the Arizona Desert,