Unfortunately, once you drop down to get the secret, you have to quickly run through the toxic waste back to where you found the BFG, or if you have an Envirosuit, activate it and take your time. Pick up the BFG10K and kill the Technicians, which will emerge where you just were around the corner. Head along the underground walkway to the next room full of guards, Gunners, and Beserkers. Pick up the ammo pack while youΓÇÖre here.
