WARNING: The following contains spoilers for Avengers #37 by Jason Aaron, Javier Garrón, Jason Keith & VC's Cory Petit, on sale now.
In "The Age of Khonshu," Moon Knight helped his god take control of the world and remake the planet in his own image. It all started with Moon Knight fighting some of the most powerful superheroes around such as Iron Fist, Doctor Strange and the Ghost Rider. He stole a bit of their power and transferred them into ankhs which he then gave to Khonshu. While the deity is doing all of this in a twisted attempt to save the universe from the threat of Mephisto, the Avengers have been fighting back, preventing Khonshu from getting the last bit of power he needs from the Starbrand child.
Now, in Avengers #37, "The Age of Khonshu" storyline comes to a close as Earth's Mightiest Heroes finally rally to defeat the moon god. Their success is in no small part thanks to a power-up that transforms Jennifer Walters, aka She-Hulk, into Marvel's new Iron Fist.
In the finale of "The Age of Khonshu," the moon god is powered by all three ankhs that give him the combined abilities of the Sorcerer Supreme, the Iron Fist and the Spirit of Vengeance. While we initially find him in space going after the Starbrand child, he is swiftly beaten back to Earth by a Phoenix Force-powered Moon Knight. Then, shortly following his return, Khonshu once again faces Black Panther.
The King of Wakanda has a connection to the powers trapped in Khonshu's ankhs which allows him to steal the necklaces away from the deity.
With Khonshu down for the count, Black Panther regroups with Captain America, Blade and She-Hulk It's now up to them to defeat the moon god's armies once and for all. And to help in that regard, Black Panther hands Blade and She-Hulk the ankhs of Doctor Strange and Iron Fist. With the necklace, Blade is transformed into the Sorcerer Supreme while Jennifer Walters becomes the Iron Hulk.
The Iron Fist is a mystical energy that currently belongs to Danny Rand. With this power, Danny is able to channel his inner energy to unleash powerful punches that can shatter through solid objects. This power is one that is nearly as old as the Earth itself, seeing as how the original Iron Fist was a member of the Avengers 1,000,000 BC. The power of the Iron Fist has had many wielders over the years and now, She-Hulk just became the latest.
With the Iron Fist ankh around her neck, She-Hulk gets a new look: the golden symbol of the Iron Fist glows on her chest, and both of her emerald fists now hold the power of Shou-Lao. She-Hulk is already a powerful superhero that has often proven unstoppable. In fact, punching through things is a specialty of hers -- and now, with the abilities of the Iron Fist, her punches have just become even more powerful.
The Iron Hulk fights besides Blade, aka the temporary Sorcerer Supreme and together, they take out Khonshu's army by themselves. Once the fighting is over, She-Hulk discards the ankh, and she returns to her normal self. It's a brief transformation, but it's a noteworthy one to be sure -- even for someone as powerful as Jennifer Walters.