>.
>Here ya' go! As soon after you push the vent button, jump
ahead and onto the rectangular pipe below you. With you
landing on it and turning around, that way you'll have
more seconds to lob a grenade (aim over the opening ) or
shoot 2 rockets into that furnace looking opening. With
you being on this pipe it gives you just enought seconds
to strike the opening to watch it explode and shut down
right before the Horde and the flying lazer robots start
aimong directly at you. So you have to be very quick: push
button, hop onto moving pipe, turn around, lob multiple
grenades/rockets and jump to hiding safety. Repeat this
for the next three times at the remaining vents.