You know, one of the most important rules for a good player is to don't check the achievement list before completing the relevant title. Sometimes these leaked even before the official distribution of a video game, inevitably revealing the narrative contents. This is precisely the case with Marvel's Avengers.
ATTENTION, CONTINUING THE READING WILL RISK IN SPOILER RISK
From the list of objectives leaked on the net you can easily guess the nature and the name of the Final Boss of the main campaign of Marvel's Avengers. New Girls Makes Good: defeat MODOK and of Kree. It will therefore be thesuper intelligent organism created by the AIM organization the main antagonist in the adventure it will bring Captain Marvel looking for Steve Roger.
How long MODOK is a character little known by fans of the film series, we appreciate the effort of Crystal Dynamics in proposing a new character, thus avoiding easy insertions of supervillains much better known, but also much more obvious.