Marvel is preparing for a big climax with the impending release of "Avengers: Infinity War," as the final fight against Thanos is being set up by the new movies of the franchise.

Fans expecting "Infinity War" to be just a mashup of all the previous Marvel movies need not worry that the film might be ruined by the sheer weight of its ambition since the writers of the movie have been using some promising source materials, which should keep the plot and story relatively fresh.

Website Comic Book has revealed the three main comic book series which "Infinity War" is based upon. This means that they may be looking into some of the traditional storylines in order to keep the movie intact despite the massive cast from the Avengers to the Guardians of the Galaxy and other superheroes who have had and will be having their own solo Marvel movies.

The first on the list is the 1991 "Infinity Gauntlet" from Jim Starlin, George Pérez, and Ron Lim. This miniseries actually put Thanos as the central supervillain in the Marvel universe and details how the mad Titan accumulated all the six Infinity Stones to form the Infinity Gauntlet, supposedly the most powerful item in the Marvel universe. The said item gives Thanos the ability to easily wipe out life in its entirety and will probably call for all the heroes in the Marvel Cinematic Universe (MCU) to unite against him.

The second comic source is 2013's "Infinity" comic books from Jonathan Hickman, where Thanos planned a diversionary strategy to keep the Avengers busy with something else while he attacks Earth. This move causes the Avengers and the Guardians of the Galaxy to become separated and fend for themselves.

The final storyline could be the most intriguing, as it involves a covert Captain America working with Tony Stark from behind the scenes while the Avengers keep up the public appearance. This is 2010's "Secret Avengers" where the team is led by Captain America after the events of "Civil War." "Infinity War" could see him back in the scene as Stark's silver bullet against Thanos.

All these could come into play once "Avengers: Infinity War" premieres on Apr. 25, 2018.