Instructions
Pick up the gun, called Redemption, found near the start of The Hollows level. The Griever attacks you at the very beginning of this level. You can't do actual damage to her, but you can use the gun to force her to move deeper in to the level. Dodge her lasers and attack the blue crystals on her belly. You need to hit her twice before she will retreat.
Take the western door. Go through the door in this room. You should be in a hallway that continues through The Hollows. Continue down the following rooms, defeating the locusts that attack you. Dive in to the water, and head northwest. You'll eventually reach a tunnel.
Climb up to the lever and pull it to set the gas pipes on fire. Go back down the tunnel, and climb up to the zip line to reach the next room. Fall in to the water pool. Go west, and kill the three Goreclaws between you and a barricaded door. Destroy the barricade to proceed.
Continue down this hall, and jump in the pool of water at the end. Swim through and jump to the other water pool until you find a path with a lever. Pull this lever. This lever slows the water current in the previous room so you can proceed. Open the locked door in this room, and defeat the enemies inside. You can ride the Grappleclaw that attacks you to clear out the other minions.
Break the crystals in your path, and continue down the hallway. Go to the southwest corner to find stairs. Climb up these stairs, and punch the metal block down in to the lower level. Drop down to the lift, and press the lever. At the top of the lift, punch the block so it lands in the middle.
Lower this lift with the lever so you can continue punching the block over. Go up to the top floor, and kill the locusts. Go over the hole. Avoid the Griever's attacks from above as you make your way down the tunnel.
Defeat the enemies in your way, smashing all of the crystals as you do so. This tunnel loops back around to an earlier area. Fall down in to this area, and destroy the crystals you had to skip earlier in the level. Go north and up the stairs. Press the lever.
Punch the truck off of the disc in the middle of this room. Move the subway car on top of it. Press the lever once more. Destroy the crystals at the front of the disc so you can punch the car down this tunnel. Go down the hall, using the car to reach high, previously inaccessible areas.
Kill the wraiths and phantom guards as you head down the hall. Go through the eastern door and up the stairs. Open the balcony door. Jump in the water to tap the pillars, coming back up to the surface so you can jump on top of one. Go north, and light the gas pipes.
Follow the tunnel south, and defeat the enemies along this tunnel. Continue going north until your passage is blocked by crystals. Find the bomb growth, and throw it at the crystal blockage. Destroy the crystals on the west side so you can light another gas pipe, triggering the bomb.
Go up the ledges to free the gear from the crystals. Pull the lever once this is completed. Enter the revealed room, and drop down. Go to the pump room, and follow the subway. Open the locked door that you find down this tunnel. Punch subway cars down the tunnel to force the tentacles to grab the car instead of you. Defeat the locusts and other enemies as they attack you.
Take the western fork, and pull the lever. Swim through the pool and under the grate. Destroy the crystals in the following room to flood it with water. Go north and continue destroying pipes along the way so the ravine is filled. You'll reach Griever at the end of this passage.