Blue attracts, Red repels, Hollow Purple combines the two and tears apart by repetitive attraction and repulsion.
Gojo uses Blue to destroy Agito. He pushes Sukuna and Mahoraga back and prepares a Red. Sukuna expects Gojo to shoot it at him, but instead Gojo fires it in the direction of the Blue that remained after Agito was crushed. Sukuna realizes this, orders Mahoraga to destroy Blue because if it collides with Red, it'll form Purple and that's the one attack that can kill Mahoraga.
Mahoraga charges at Blue, but because it has already adapted to it, its attraction does not affect it; Gojo uses this to his advantage by having his own Blue pull him, making him reach it before Mahoraga does in order to protect it from destruction.
Sukuna appears from Mahoraga's shadow, shoots Piercing Max Elephant Water at Red in order to stimulate it and make it explode before the merging, but Gojo strengthens Blue with a chant, making its attraction stronger and absorbing the water attack instead. Oh no, there's no time for another attack to prevent the collision. Oh fuck, they're about to merge. Oh shit, we're too close. Oh n- BOOOOOOOOOOOOOOM!
