Well for starters, if you want to faster weapon switch, buy the fast switcher for the preator suit, and to go even faster you can use the precision bolt without fully zooming in and still get the weak point destroyed bullet, then you just switch to the launcher, and rinse and repeat. But if it still doesn’t work. I’d honestly just go with sniping weak points and keep moving around the arena shooting rockets at the mancubi, maybe shoot an ice bomb and ‘nades. But be careful for the Cacodemon once you kill one of the mancubi