"You Must Act" (お前がやるんだ, Omae ga yarunda) is chapter 8 of the Boruto manga.
Momoshiki finishes changing from absorbing Kinshiki as the others look on. He releases a massive energy that cuts through the God Tree. He swiftly punches and kicks Darui into one of the branches of the God Tree. He goes after Gaara, who blocks his punch with sand, but Momoshiki's hair goes around it, binding Gaara by his limbs, waist and neck, kneeing him on the back and letting him fall to the ground. He falls near Chōjūrō and Kurotsuchi, his fall allowing Momoshiki to kick Chōjūrō from behind. Kurotsuchi tries punching him, but he blocks it, and lands a punch of his own on her chest, causing her to collapse as well. Naruto and Sasuke reach him, while Boruto watches from afar, noticing how he easily took out the Kage. Naruto and Sasuke noticed how much he's changed, Naruto calling him a monster, much to Momoshiki's amusement, who considers Naruto one as well. Momoshiki and Naruto exchange blows, Momoshiki managing to kick Naruto away. He flies over to Naruto to land another hit, but Naruto dodges it, and blocks the next one as he enters Six Paths Sage Mode, landing his own hits and sending Momoshiki flying. Sasuke lands a hit of his own, sending Momoshiki down to the severed God Tree. Momoshiki creates wooden dragons out of it, some of which Sasuke beheads before being caught by one. The head holding Sasuke is cut by Naruto, having fully manifested Kurama. Momoshiki gathers the environment and creates a giant golem around himself to fight him. He manages to grab Kurama by the throat, but Sasuke intervenes, armouring Kurama with Susanoo, allowing Naruto to destroy one of the golem's arms. Using Susanoo's sword, they cut the golem down, Momoshiki falling to the ground. Naruto and Sasuke dispel Kurama and Susanoo. Boruto is in awe. Darui asks if it's over, but Naruto denies it. Kurotsuchi suggests they pull off a grand collaborative technique, but Chōjūrō and Gaara point out that would get them back to square one. Naruto notices Katasuke and his camera man in the distance. Against Naruto's warning, Katasuke fires several ninjutsu from his Kote, which Momoshiki readily absorbs, reinvigorating him. Momoshiki traps the five Kage and Sasuke with a shadow jutsu from the Nara clan, and further pins Naruto down with black receivers. Boruto thinks back to Sasuke telling him that should the worst happen and they can't fight anymore, Boruto has to act. Momoshiki prepares a jutsu against the Kage and Sasuke, and Boruto begins forming his Rasengan.
In the movie, the four Kage were just thrown back by Momoshiki's shockwave, but in the chapter, Momoshiki personally fought and defeated each of them.
Naruto activated Six Paths Sage Mode already after he engaged Momoshiki, although in the movie, he entered it beforehand. Similarly, Sasuke didn't take off his cloak, but wore it during the rest of the battle.
In the movie, Sasuke escaped Momoshiki's Shadow Imitation Technique along with Boruto and then prompted him to use Vanishing Rasengan. However, in the chapter, both Sasuke and the five Kage were caught, and Sasuke's instruction for Boruto had happened before they departed to the other dimension, which prompts Boruto to act in the present time.