War of the Realms is looking to be one of Marvel's better comic book events, as the story has been teased for a long time now. Jason Aaron planted the seeds during the second arc of his lengthy Thor run, which started with Thor Odinson, switched to Jane Foster, and cycled back to Odinson. Amazingly, that run is still going and it will probably tie-in to the big event in an eventful way.
Unsurprisingly, there will be a tie-in mini-series that focuses on other characters but this one might be more important than most. Marvel and the McElroy Family have announced War of the Realms: Journey Into Mystery and it stars Thor's baby sister. This will probably be controversial for many but the character is a literal baby, with Spider-Man (Miles Morales), Hawkeye (Kate Bishop), Wonder Man, and others taking care of a baby because the world depends on it.
(Marvel Comics)

Here's how the McElroys have described the premise:
To be honest, it's nice seeing the Journey Into Mystery name being used again since this is where Thor, well the Marvel version anyway, made his debut. Modern comic book fans also associate the title with Kieron Gillen's magnificent run that starred a kid version of Loki, which blew away everyone's expectations.
War of the Realms: Journey Into Mystery #1 comes out on April 10.
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