Run down the walkway, you were facing, into the room you have to go through. There are some crates you can nab the goods inside of them. Enter the doorway into the next room full of Majini toting guns. Beautiful, just beautiful.
You can ambush them by pulling out a sniper rifle and getting a couple headshots before they can react to you.
Run down the stairs, whip out your sniper rifle and headshot the closest Majini and kill his friends (one might be hiding in one of the doorways or behind some crates). If you're fast enough, you can dispatch all of them before they can even react or shoot you.
After killing all the Majini so far, you run into more of them. Be careful as two of them may be carrying Stun Rods that can take out at least 1/4 to 1/3 of your health. It's also capable of striking you and your partner. A Shotgun is capable of dispatching them and pushing them back.
Killing all the Majini in the room will allow you to safely enter a room on the left, with a Red Herb and some crates will ammo. A Stun rod wielding or gun-toting Majini will jump down to attack you. after breaking the crates.
Enter the door, at the end of the room. It leads to a quiet room before leading into another room filled with about seven or eight Majini. There is little to no cover when you initially enter the room. Stay to the left of the entrance and pick off the Majini from there. A Green Herb can be picked up before climbing the stairs where you'll meet the final three or four baddies.
After killing the Majini, you can enter the elevator doors to head deeper into the heart of the facility.
You will face a U-shaped room filled with more Licker Betas. Joy. Kill them all however you see fit. The first wave is the hardest as there will be large amount of them. Be cautious as the vents will have some Lickers crawl out of them, behind you, as you walk passed them. You can sneak up on them and open fire on them. However, they may sense you as you do this. Just run back and pick them off until they get close and kill them with a shotgun. The second wave in the other half of the room will be smaller, but they will be more sensitive to sound and your presence if you get too close.
You will be able to nab up to five Lion Hearts in the waves of Lickers.
At the end of the corridor with the Beta Licker threat, you'll find a door. Head on through, and you'll be brought to a quiet area. Head down the metal grate to a ladder. Jump down and enjoy the welcoming committee greet you. Work your way around the conveyor belt, collecting goods and killing enemies as you go. Some will throw grenades and other explosives at you. Prioritize their who to kill first (along with Stun Rod-equipped thugs) before anyone else's. Thankfully, the roving boxes on the conveyor belt will provide large amounts of cover for you to utilize. You can pick off the mobs by sniping them all. Head to the raised platform via a staircase opposite to where you initially dropped down. This will grant you access to the conveyor belt immediately before the goods enter the incinerator. Begin pressing against the tide here, using the center unmoving portion of the conveyor belt to dodge incoming boxes. Your ever-clumsy AI partner will complicate the issue, no doubt, but just worry about yourself here. When you can grab onto an otherwise-inaccessible platform to your right, do so. Use the switch there to shut down the conveyor belt before running up the stairs and busting through the door you encounter with your partner's assistance.
The scene you encounter here is even more violent and dangerous than the area surrounding the previous conveyor belt. The conveyor belt here is loaded to the brim with explosives. After collecting the goods to your left, jump on the conveyor belt, but only after priming your jump with some shots to the nearest explosives, thus giving you some padding heading forward as you gain your footing. Then, book it. You can pick off the mobs by sniping them all before jumping onto the conveyor belt. You can stay in the middle of the conveyor belt and pick off mobs as you bolt down to the other side. Some mobs will start running down the belt to greet you. Blow them to hell with the convenient explosives as they are toting annoying riot shield and stun rods.
Shut down the conveyor belt via the lever there and then run down the nearby staircase. I recommend leaving a few explosives on the line, you might need them in a bit.
Here you can pick up a new machinegun, the SIG 556. A decent machinegun compared to the AK-74.
Here you will find out the conveyor belt's power is off. You must re-route the power to them through some weird pod-looking things. At the power switches, you can nab some machinegun ammo for your new toy and a Red Herb. After successfully re-routing the power, you hear a weird scream. One of the pods are open and something crawled out.
As you run to the conveyor belt, you meet a new friend aptly named the Reaper. An insect with a bulletproof carapace that produces a mist to hide it's weak spots that pop open occasionally- some white fleshy orbs that appear on it's chest, back, and sides. If you get too close, it will instantly kill you by grabbing you and turning you into a human pin cushion with it's stabbing pincers. You can run passed it and lure it to the explosives and weaken it with those helpful explosive crates that way until it gets close and shoot it with your shotgun or magnum (shotgun highly recommended as it is less likely to miss the orbs that protrude from it's body). Successfully killing it will net you a 5k gold Power Stone.
Run back to the conveyor belt you just re-routed and turn it on to see corpses leading into a furnace. One line will have boxes occasionally coming down and the other three belts will have "dead" bodies. Some will actually be dead, but some will springe on you and try to attack you and possibly take you into the furnace with it because it wants a friend. Killing them will net you new jewelry- Dead Bride's Necklace. You can just run by them until you reach where they come out and onto the platform.
As you make your way to the end, you will reach the boss of the chapter. There are some crates that hold some Flame rounds for a Grenade Launcher if you brought one and some Incendiary grenades.
If you haven't guessed already, the key to this boss is FIRE. Burn the boss with a convenient refillable flamethrower. This boss is just like the first boss you fought in the game, but a little more advanced and deadly. Shoot it's glowing orbs to stun it for your partner to burn it. The crates in the boss room will have some health items and ammo if you need it. You won't have to refill the flamethrower more than twice if you burned the boss and dealt enough damage to him. Be careful as his drops to about 3/4 or less he starts running away more and you have to be fast.
If you don't want to concern yourself with burning him, shooting an RPG at his face will end the boss fight.