Take this with a grain of salt but there’s a new rumor indicating that the next blockbuster film from Marvel Studios will be based on Marvel Comics’ ULTIMATUM storyline from 2009.

The rumor comes from MCU Cosmic, a site that also posted initial rumors about Eternals and the Hawkeye series before it became official, which adds credence to this latest development. MCU’s version of ULTIMATUM may also pave the way for X-Men and the Fantastic Four to be introduced into the cinematic universe and carry the torch after the Avengers.

ULTIMATUM was a five-issue miniseries written by Jeph Loeb in 2009. It tells the story of Magneto in the Ultimates universe (Earth-1610) attempting to destroy the world as revenge after the deaths of his children, Wanda and Pietro Maximoff. Jeph Loeb’s writing was critically panned, despite having impressive reviews on David Finch’s art, which was also reflected in its sales drop as the issues went on.

While it’s possible for the X-Men and the Fantastic Four to be introduced in an ULTIMATUM-based story, it’s also worth noting that the original source saw the deaths of many Marvel Comics characters, such as Doctor Strange, Thor, and Valkyrie (among others). If MCU will adapt ULTIMATUM, expect beloved MCU characters to make their permanent exit.