Marvel's massive Phase Three slate is already well under way, with Captain America: Civil War currently in post-production, and principal photography about to start on Doctor Strange in Atlanta. This massive phase will come to a close with Avengers: Infinity War Part I and Avengers: Infinity War - Part II, slated for release in 2018 and 2019 respectively, with production slated to begin in late 2016. While there is very little we know about this two-part adventure, a new rumor has surfaced from Bleeding Cool, which claims that both movies will be an incredibly costly endeavor for Marvel Studios, to the tune of $1 billion.

The report claims that the "above-the-line" fees paid out to screenwriters Christopher Markus and Stephen McFeely, directors Anthony Russo and Joe Russo, plus the producers and primary actors, will cost Marvel $400 million alone. The site's "well sourced comic book film insiders" claim that Robert Downey Jr. gets half of the total budget for actors, which isn't surprising, given how much he's made for the MCU thus far. A report from July revealed that the actor pulled in a whopping $80 million this year, $40 million from the back end of Avengers: Age of Ultron and another $40 million for his work on the upcoming Captain America: Civil War.

RELATED: Josh Brolin Wants to Play Cable Again in the MCU Even Though He's Thanos

None of this has been confirmed by Marvel quite yet. The report goes on to claim that the filmmakers haven't even decided on a plot, and Christopher Markus and Stephen McFeely don't have a finished screenplay at this time. The writers and directors Anthony Russo and Joe Russo recently wrapped production on Captain America: Civil War, so it remains to be seen when work will begin on the two-part Infinity War script. The report also claims that a number of Avengers aren't expected to make it out alive.

Marvel Studios president Kevin Feige revealed that Phase Three will mark the end of a big part of the Marvel Cinematic Universe, and while he didn't specifically say that certain characters will die, he did hint that the "roster is always changing." Most of the original Avengers are nearing the end of their multi-picture contracts with the studio, so it wouldn't be surprising to see some of Earth's Mightiest Heroes pass away on the big screen.

Captain America: Civil War will feature almost all of the Avengers, old and new, with the exception of Thor (Chris Hemsworth) and Hulk (Mark Ruffalo). This massive adventure is said to set the stage for Avengers: Infinity War Part I and Avengers: Infinity War - Part II, but we won't know for sure until it hits theaters on May 6, 2016. What do you think about Marvel spending a reported $1 billion on Avengers: Infinity War Part I and Avengers: Infinity War - Part II?