There is not much known about "X-Men: Dark Phoenix" at the moment. However, as with any other installments, it is expected to come with real twists and surprises especially now that the franchise is about to undergo a major shake-up, courtesy of the Disney and Fox merger. If the latest rumor is anything to go by, one of those bombshells could be the possible appearance of Onslaught.

Debuting in the comics "X-Man" #15, Onslaught is a psionic entity created from the consciousness of both Professor X and Magneto. Xavier once tried to shut down Magneto's mind using his telepathic powers, leaving the latter catatonic. During the psionic contact, Magneto's psyche imprinted on Xavier's subconscious and commingled with every long-suppressed negative feeling the professor had so far endured. This gave birth to a third personality called Onslaught, which was awakened when anti-mutants human killed a mutant near the secret base of the X-Men.

The entity possesses the combined abilities of Professor X, Magneto, Franklin Richards, and Nate Grey, making him one of the most powerful villains in the Marvel comics.

The theory that he may be featured in "Dark Phoenix" stems from Entertainment Weekly's description of the movie. As reported, it sees how Jean Grey (Sophie Turner) transforms into Phoenix when they are dispatched to space for a mission. It turns out the reason behind the heroic mission is Xavier's "growing ego." That particular phrase used has fans believing it could be a hint at the character's transformation into Onslaught.

However, the film is expected to make a few changes to how the entity is created.

It has been rumored that "X-Men: Dark Phoenix" will feature the death of one of the major characters. While the odds are higher for Jennifer Lawrence's Mystique to be the casualty, Magneto's (Michael Fassbender) ability to go against the Dark Phoenix makes him a plausible candidate for death, too. This could lead to the creation of Onslaught. However, instead of Charles (James McAvoy) using his powers to wipe out Magneto's mind, Comic Book predicts he may use it to store some of his friend's psyche before his physical body dies.

Whether this is the case or not, fans are in for an emotional ride. As McAvoy previously teased, there will be a lot of sacrifice and suffering on top of the massive twist that will change the franchise forever.

"X-Men: Dark Phoenix" opens in cinemas on Nov. 2, 2018.