Chapter 16 starts with a cutscene. Once you have control of Isaac again grab some cover. Up the railing there is a good spot. Grab what supplies you need, use the work bench and then use the repel station to start your descent.
This is basically the same as climbing up. To run down the the side of the tunnel, hold the L1/Left Bumber button. You can use that same button to quickly dodeg out of the way. During your climb down you will have a Unitologist shooting at your from the lowering platform. They will be hard to snipe from afar, if you have something with a large blast radius this would be the time to use it. You can also keep your distance, then bum rush him when you close in on the platofrm. When you get ot the bottom, use the prompt button to hop down.
There are two leapers waiting for you here. Kill them, and grab some cover and shoot the Unitologist soldiers. Then grab whatever supplies you need and head to the nearest repel point to continue downward. There will be more Unitologists this time, not only on the lowering platform, but on walkways as well. See if you can spot any red barrels next to them, if so, shoot the barrels for an easy kill.
Once at the bottom of this climb, get to cover again and take down the three commandos on the walkway here. Make the rocket commandos a priority as they are the most dangerous. Complete the puzzle to open the door and head in this room to grab an audiolog, there is also a suit kiosk to use here. Then head through the door into the next room.
There’s three swarm on the walkway coming for you. Take them out quickly before the Unitologists can be ressurected. After you kill the swarm/ressurected Unitologists, make your way down using the next repel station..
There’s a bunch of Unitologists in this climb. About halfway down you will run into a crawler. You can yeild some ground when fighting these guys, making sure you don’t end up getting overran. As you catch up with the platform a cutscene will trigger and you will meet the alien necromorph.
The alien necromorph will come after you. Stasis can be a lifesaver here, take of the big guy’s arms. After one arm is gone it will tumble down the cliff. Continue down the wall and jump on to the platform below. If you shot off and arm you will find the alien necromorph fighting the Unitologists. Let them take each other out before joining in the fray.
Head right and grab what supplies you need. Go through the door and follow this passage to the another repel point to continue your descent.
Another alien necromorph will come racing up the wall to greet you. Hit him with stasis and blast him with your most powerful weapon. Try not to advance too quickly or you will trigger a slew of crawlers as well. However, as you continue you will be forced to deal with the another wave of crawlers and another alien necromorph, this time simultaneously. Try getting some quick shots off on the alien necromorph, then blast the little guys when they get close. Keep the alien in stasis so that he stays off your back. After the crawlers are dealt with, hit the big with everything you have.
Keep descending and you will find a giant fan. Slowly approach it and an alien necromorph will run right into it. After the fan has done your dirty work, hit it with stasis and slip between the frozen blades. A little further down and you will get a quicktime sequence. After you complete it the chapter will end.
Article from Gamersyndrome.com