[Emperor Pan I]

For the most part so far the only real lead up was New Avengers, and the last couple issues of mighty Avengers.

Those are Skrulls with a ****load of powers based on the heroes from Earth. Some Skrulls have infiltrated certain groups, taking the place of a hero, with powers and everything and set up for the invasion which you see in that image of the rest of the Skrulls arriving all jacked with powers.