Rockets are fine, but they have a limited supply of bullets. However, bosses’ machine guns received a significant upgrade. Linear Fusions are impossible to aim at in the midst of this chaos
You may now use it, and it’s a waste of time to attack most Nightmare opponents without it, since you’ll do far less damage. Just make sure you have the buff before you start burning heavy or super on the yellow bar Nightmare bosses, which are continually generating Nightmare bearer foes.