A brief recap. This mission is mainly divided into four parts:
What have we changed? Parts 1, 3, and 4. Rather than dividing this 2.0 upgrade into the chapters Bungie provides for you, we'll be meandering our way from start to finish via the segments I have selected above.
Part - 1:
You begin the mission with a Rocket Launcher and Assault Rifle. Neither are important to the mission, so we'll be ditching them right from the get-go. First, do a 180 and check out all the scattered weapons from the downed Pelican. There are three Battle Rifles laying around in the clutter, so grab one in place of your AR and collect the ammo from the rest. Now you're ready to head through the cave towards the control room tower.
The Hammer alone is all you need. My recommendation is trying this on lower difficulties first so you can get the hang of it. Admittedly, they can be rather tricky to pull off at first, but once you've gotten used to it, you'll be able to scale the tower with ease.
Your next goal is to obtain the Infinite Laser. Follow this path to reach Sergeant Johnson who is perched on the ledge to the far left.
Now for the task of actually collecting the Laser. The one that Johnson currently wields is NOT the Laser we're looking for. Switch over to your BR and shoot him once in the head. He should drop the Laser and fall over "dead". If you have to, juggle it away from his body so he won't pick it up again when he revives, though normally it just falls off the side on its own. When he revives, he'll be holding a brand new Laser. This one, and every one he gets afterwards, will have an infinite number of charges for you to use. To collect it, stand close to him and shoot him in the head once again. My advice would be to swap out the Hammer for the Laser while it's in midair to avoid having it fall off the cliff. Here's a better illustration on how it's done.
You can now sit back and casually blast all of the Flood you see swarming the top of the tower. When the tower is clear, you'll be able to head through the blast door and make your way towards Guilty Spark. If you want to keep your Laser for later, I recommend taking any weapon you see laying around the top of the tower and juggling it with the Laser all the way to the control room door. Since the game takes away all your weapons after the Guilty Spark fight, you'll want to leave it right out side like so...
Part - 2:
The battle against Spark couldn't be more simple. Each time he fires his death ray, he'll either fire it too far to the left or to the right. In either case, you can easily just side-step in the opposite direction to avoid it without any trouble. Heck, I even jump over it just for fun. Though this is also in 1.0, I'll demonstrate it again here.
Note that you can't actually kill him until Johnson hits him once with his own Laser, but once he does, take it, blast Spark a few times, jump over his beam when he shoots, and after a few hits the Light Bulb will go out permanently.
Part - 3:
Collect the Laser once you're back outside and use it to blast and Flood combat forms between here and the blast door. Use the Assault Rifle against the Infection Flood. I'd also advise allowing the Arbiter to always go first to cause a distraction. Your goal is to make it to the Warthog with full shields, so the less hits you take, the better off you'll be in the long run.
Between you and the Arbiter, dealing with the Flood while running around the ledge should be a cakewalk. If you ever need shields, bash a Combat form that is already being engaged by the Arbiter. This takes the pressure off completely.
For this next part, I recommend ditching the AR for a pair of Plasma Rifles. Go ahead and use the Laser against the five Carrier Flood in the corridor up ahead. Then switch over to your Plasma Rifles and mop up the swarm of Infection Flood that will result from the attack. Arbiter will run ahead and distract most of them for you.