This level is a sniper's dream. You start with 64 extra rounds for your trusty S2 AM Sniper Rifle (you can normally only carry 24). And if you play your cards right, you can go through 404 rounds by the end of the level. Playing on Legendary, you'll need every one of them.
Since we'll be relying on our sniper rifle throughout much of the level, I'll take a moment to impart some sniping tips.
Truth and Reconciliation
As the level begins, Cortana tells the marines to stay put while you move in to thin the ranks of the Covenant. There's a nice little rock with a crook in it you can snipe through against the wall on the right. Get comfy and start shooting. Take out the Shade gunner then hit the closest enemies first (or the ones most likely to see you) and work your way back. There are two elites, two jackals, and seven grunts here.
If you leave one grunt alive, you can stealthily move into this area far enough to trigger the next group of Covenant without getting your marines involved. Quickly retreat and you can continue to snipe from safety. One elite and two grunts will rush into the area. They are followed by four grunts, which are then followed by two jackals. You can get a checkpoint without the Covenant even seeing you.
Head slowly into the next area and you should see a few grunts and a jackal pacing around on top of the ledge in front of you. Sniping them will trigger an elite and a few more grunts to move into the open to the left of the ledge. Finish them off and move forward. Be careful here. There's an elite that likes to hide in the little cul-de-sac to the right at the base of the ledge. And there's a Shade near him on the ledge that's easy to miss.
There is a health pack here and two boxes of ammo for your sniper rifle. Don't pick up either of these yet. There are 16 rounds in each box, so unless you're 16 or more rounds from a full load, you'll end up losing some if you pick up a box. Even if you're just one round shy of a full load, you can still pick up a box of ammo. You'll just pick up 1 bullet while the other 15 disappear into thin air. So throughout this walkthrough, unless it's an emergency only pick up one box of ammo at a time, and only if you have 8 or less extra rounds for your rifle. You might have to do a lot of backtracking, but it's worth it.
Now that we have that squared away, there are a total of three elites, one jackal, and fourteen grunts in this area. You should still have one elite and about half the grunts to deal with, so move on ahead and take them out. Snipe the elite if you can then switch to your assault rifle. One of the few things the assault rifle is good for is mowing down gaggles of grunts, and there are many here to mow. Three of the grunts usually come from around the corner leading to the next area, so keep an eye out for them. You might want to switch your assault rifle out now for something more useful. I'd suggest the plasma rifle.
The next area includes two elites, four jackals, and nine or ten grunts for your sniping pleasure. There are two ways up here. One goes through the middle and the other curves around to the left. One of the elites should come wandering up to the ledge just to the left of the middle way up. Shoot him then head around to the left and you'll find two jackals to kill. Further around to the left you might be able to take out the other elite, but he's tricky. Snipe as much as you can from down below, going back and forth and sneaking around as necessary, then move up on the left.
This area gets messy. Once you move up the marines will engage the Covenant creating what seems like total chaos after all that sniping. Try to stay under cover and snipe as much as you can. Use the chaos to take out anyone in the Shades then go for the elite and jackals. Be careful of the Shade tucked away in the far left corner. You'll be coming up near it, and it's almost always manned. To make matters worse, a Covenant dropship will soon arrive. It's carrying one elite, three jackals, and one grunt. To make matters better, there's an active camouflage tucked away in the trees. Grab it if things start to get really nasty. Then run around and bash things in the back. Another bit of advice that holds for the entire game, but is especially relevant here, is to ignore the marines. While it is an awful lot of fun to rush in with them and try to save as many as you can, it will make you're job considerably easier to hang back and use the confusion they create to snipe at some of the nastier enemies.
A narrow corridor leads to the final outdoor area of this level. If you move towards it, two elites and three or four grunts will rush out to greet you. Trigger them from the ledge above. This will make your job of raining grenades on them that much easier. These are the first enemies in the level you can't really snipe, so if grenades don't work you'll have to vent as much plasma as you can on them as they run around to get to you. By now you'll probably need that health kit and a box of sniper rifle ammo, so head back and get them.
As you move ahead, you'll see one last rock against the wall on the right before the corridor opens up into the final area. It's just perfect for peeking around to snipe and will be your home away from home until you board the Truth and Reconciliation.
The first group of enemies already waiting for you includes one elite, two jackals, and eight or nine grunts. There are no less than five Shades here for them to hop in as well, so check them often. One of the Shades is sitting on the high ledge to your left as you enter this area. It's easy to overlook, so be careful.
Move cautiously forward, stopping near cover, eliminating anything that comes into view. If at any point you get overwhelmed, fall back into the narrow corridor behind your trusty rock. The Covenant won't pursue you past here.
Once you send this group to Covie heaven, the battle really gets going. Multiple waves of enemies will come down the lift. Each one is comprised of an elite, a couple of jackals, and half a dozen grunts give or take a few. At one point a Covenant dropship will show up and drop off some jackals and grunts on the far side of the gravity lift. They will soon be followed by more waves from the ship.
As each wave appears, get their attention. Shooting at them works well for this. Fall back to your rock and wait for them to follow. They'll end up near you in a big bunch just asking for grenades. Oblige them then snipe any leftovers.
On the far side of the gravity lift are a few dead marines who have sacrificed themselves to leave four more boxes of ammo and a health pack for you. You'll definitely want to save this health pack until you're ready to board the ship, but you should grab the sniper rifle ammo if you can get to it. A good time to make a break for it is when the Covenant dropship flies in.
The last Covenant you will face here are two hunters, the first you face in the game. In case you don't already know, one shot from a pistol or sniper rifle into the soft orange flesh underneath their armor will kill them instantly. The easiest way to get a shot in is to sneak around and shoot them in the back. Another method is to get close enough to them so that they stop firing their fuel rod gun and charge you. You can see their guns glowing as they prepare to fire, so dodge at the appropriate moment. Getting close to them shouldn't be a problem. Then either sidestep and shoot them in the back after they charge past or back up and shoot them in the tummy as they swing their shield up and hopefully miss you. Another important thing to note when dealing with hunters is that they always come in pairs. If you rush them, try to keep them in a line so one is always behind the other. That way you only have to deal with one at a time. After they are taken care of, grab the health pack, fill up your sniper rifle, grab a plasma pistol and get ready for some real fighting.
Into the Belly of the Beast
You are about to get your ass handed to you on a platter. Many consider this to be the hardest battle in the entire game. Almost a dozen waves of enemies are about to pour out of those doors. But there is a brief lull before the storm, so acclimate yourself to your new surroundings. There is an active camouflage and a health pack in one corner of the room. They will come in very handy.
The first door will flicker and open usually revealing a stealth elite who can quickly decimate your ranks. Pour on the plasma in his direction. Getting hit partially negates his active camouflage, making him visible enough for your myopic marines to lend you a hand. Immediately the rest of the waves will begin to give you a warm welcome.
The order of these waves is random, but there are two types. They will either produce a few jackals and several grunts or they will produce a few jackals, several grunts, and a golden elite commander. This guy can go through your marines in seconds. Either way, when you see a door flickering move towards it. As it opens toss a grenade in. If there's a gold elite among their ranks, fire a charged plasma shot at him. Concentrate all your fire on him until he goes down. Stick a plasma grenade to him if he's ever stunned or against an obstacle. If there isn't a commander, toss a second grenade deep into the hall. Follow up as quickly as possible, using charged plasma shots to take out each jackal's shield. Switch out your plasma pistol if it gets low. You'll be going through a lot of ammo here.
Eventually the waves will probably get ahead of you. You won't be there to toss a grenade while the Covenant are clustered and they'll spread out across the room. Hang on as long as possible then pick up the active camouflage. It takes a second to fully conceal you, so you actually want to wait until the moment before the last possible moment. Once you're invisible, move as fast as possible positioning yourself behind Covenant and whacking them. The elite commanders are your first priority of course, but hit any target that presents its backside to you. Throw grenades, but don't shoot. Generally just make the most of your time.
By the time your active camouflage runs out you should be in much better shape. All the waves should be in the open and nearly all the elite commanders should be dead. The last part of this strategy requires access to the hallways, so use the last bit of invisibility to duck in. If you can manage it, go into the hallways leading to the next area, not the darkened dead-ends. From here you can switch to your sniper rifle and go back to slowly whittling down their numbers. Move through the halls and shoot from different entrances to keep them on their toes. If an elite commander comes in after you, hit him with a charged plasma shot. If he continues after you, he'll be really close, so switch back to your sniper rifle and send a few rounds through him. Slowly but surely you should be able to finish off the last of the waves.
Once you think you have control of the area, two hunters will show up. You should still be in the hallways and have some rounds left in your sniper rifle. Move back and forth between the entrances to try and get behind them. If you have to move out into the open, use the same tactics you did for the last two hunters. Let them charge you then back up and shoot them in the gut or sidestep and shoot them in the back. After the initial assault, these guys should be easy. Now you really have control of the area. Scavenge through the whole place.
The door to the next area has opened now and two grunts are waiting for you behind it. Dispose of them. Going around this next corner has the annoying consequence of triggering a small wave of enemies to appear behind you. So each time you go around to fire off a few shots, you'll have to go back and kill off either two grunts or a jackal. This shouldn't be a problem if you're aware they're coming. Because of them though, I find it easier to use charged plasma shots and a needler here. Be careful to not lose track of your sniper rifle in the confusion. There will be two elites and several grunts here. By the time you're done the ground should be littered with weapons. Pick up your sniper rifle and keep your plasma pistol.
As you step out into the next area you'll see that you're on the upper level of a small hangar. There are two elites and four jackals on the ledge with you. Since you have a pile of weapons behind you just keep sending charged plasma shots towards them. Use any cover available and follow up whenever possible to finish them off. Keep moving around and going through those plasma pistols. With your height advantage, you can snipe at any Covenant down below. Plasma rifles work well at this range also. And don't be afraid to use up those plasma pistols. They'll go to waste if you don't.
Once you're done playing, move into the halls leading down to the lower level. There are two grunts and two jackals ahead. Use charged plasma shots to take them all down. If you're lucky the elite further on will have his back turned to you. Be careful and you can take him out from behind.
Out on the lower floor of the hangar, right in front of you now, should be a health pack and three boxes of ammo for your sniper rifle. Two by the body on the right, one on the left. From the hall you should be able to pick off almost everyone in this area with your sniper rifle. Move back upstairs every once in a while to get a different angle. Every time you get down to 8 extra rounds for the rifle, run out and pick up another box of ammo. Once the initial enemies are cleared away, there will be a brief pause before more waves of Covenant move in. Wipe them out as you did the previous enemies, moving back and forth between levels for a change of scenery.
Move into the next set of halls around a corner or two and you come to a long hall with two dead-ends to the left. There are two jackals, three grunts, and an elite lurking around here. The elite likes to hide in one of the dead-end corridors, so be sneaky and snipe him for around the corner. Moving ahead around the next corner will trigger a load point. This causes a door to close behind you, sealing off the first part of the ship. So go back and take anything you can, especially sniper rifle ammo, before moving on. I know I said not to pick up a box if doing so will waste ammunition, but I'll make an exception this time.
The next area will take quite a while to clear out. It's a large three-story hangar capable of holding two Covenant dropships. There are four boxes of rifle ammo and a health pack on the far side of the first bay and four more and an over shield on the far side of the second bay. That's 128 sniper rounds you have access to, so snipe away. One elite and a few jackals and grunts will snipe back at you from the second story, so taking them out should be a priority. Work through the ranks of the enemy until you've cleared out everyone here. Multiple waves of bad guys will come through the doors to make you're life difficult, but it can sometimes take a lot of wandering to trigger them. Always keep track of the door you used to originally enter the area though. You'll want to head back there as soon as a new wave arrives. Sometimes there are Covenant coming out of this door as you're trying to get in it, but a grenade should clear the way nicely. Once you're safely inside, switch back to sniping until the room is once again clear.
Can you guess what the last wave of enemies is? That's right, hunters! There's ample cover and several ways to sneak around behind them. Go to it.
Move into the next set of halls and clear out the grunts and elite lurking around the corner here with your sniper rifle. I would advise grabbing the over shield now. There are a couple of stealth elites just ahead and they can be a real pain. You're next health pack is far away, so be careful. Snipe the grunts and elites if you can distinguish where they are, but you'll probably have to switch to your secondary weapon. Run in and spray plasma until you find where they're hiding. They'll retreat all the way out onto the second story ledge if you let them.
Once you're ready for the second story, peek out and continue to snipe. Don't forget about your grenades. If there are too many to peek out and snipe at, they're just perfect for some grenades. Once they're cleared out, move ahead.
Half way along this ledge, a group of Covenant will suddenly appear behind you and move to attack. Rather than getting caught between a rock and a hard place, just hop down to the floor below. The fall won't cause any permanent damage. Now you have those Covenant goons in a much better position. Move back through the halls and up to the second story. They should be easy prey for your mad sniping skills.
At the end of the second story ledge is a closed door. There are many Covenant on the other side, so open it and bounce a few frag grenades deep into their midst. Retreat and fire at any that come after you. Repeat until the way up is free from worry. Only a few more grunts and jackals and one lonely elite stand between you and the third story.
Moving out onto the third story ledge and peering to your right through your scope you should a door opening the way for an elite and his grunty cohorts. A few well-placed shots will take care of them.
As you move around the ledge be careful. After you get half way along the far side two groups of Covenant will show up. One from in front, and one from behind. Look for them to show up on your motion tracker. Fighting a two front war is strategic suicide, so we're going to get the heck out of here. Look down and you'll see a platform jutting out on the second story below you. Fall down onto it and you're safe. Go all the way down and grab ammo if you need to then move back up to the third story. The Covenant probably didn't even see you, so they should be easy to exterminate.
You might think the way is clear after all that. Sadly, you'd be wrong. As you move to the last door on the third story out of this area, yet another congregation of Covenant will come from both sides to end your intrusion. You know what to do. Drop down, grab ammo if necessary, go back up, and snipe them. Finally you're done with that accursed hangar. Well, for now.
There is a much needed health pack waiting for you ahead along with 48 more sniper rounds. They're tucked away to the left just before the control room. The control room has three entrances, so feel free to move around. Start off by sniping an elite to wake everybody up then go through the ranks. There are a couple of elites, one jackal, and several grunts in here. To top it all off there's a gold elite commander as well. Keep a plasma pistol handy in case he comes after you. In these narrow halls a charged shot followed by a few sniper rounds will take him out nicely. You won't get a checkpoint until you take out the grunts lurking on the other side of the door out of here. Just keep sniping then keep on moving.
The halls ahead hold a few grunts and three pairs of jackals. You can snipe them all if you're careful. There's an empty brig off to the left, but don't worry about that yet. Make sure these halls are totally cleared out and find the second brig where Keyes is being held. You can peek in and snipe any grunts around. There are also two stealth elites and an elite commander on guard. Now you can go back into the empty brig. There's a health pack in a cell and an active camouflage hidden away in the back. Grab it and run as fast as you can to free Keyes. You should have plenty of time to sneak in and beat everyone down. Now just hit the switch and you're set.
Shut Up and Get Behind Me... Sir
Yay, Keyes is free! Don't listen to him. He's really very happy to see you. Now you just have to get him out alive. Almost immediately two stealth elites will come in, so have a grenade waiting for them, snipe them, or just hose them down with plasma. There are two jackals waiting out in the halls too. One of the now open cells has one last box of sniper rifle ammo and a health pack for you. Grab them when you need them.
Move out and head down the hall. An elite and some grunts are waiting off to the left, so bounce a frag grenade or two around for them. Sniping is a little difficult since the marines rush ahead so often, so just rush ahead with them shooting lots of charged plasma shots and throwing lots of grenades.
There are a few more groups of Covenant ahead. Snipe if you can then follow up with grenades and charged plasma shots. Try to take the brunt of the enemy fire. You'll need as many marines alive as possible for the upcoming skirmish.
When you get back to the control room, you find that there are now three stealth elites guarding it. From the doorway you can carefully deduce where one must be and fire a couple of rounds through one of them. The other two will come straight for you, so take careful aim and send two more rounds through another. Keep backing up and hose down the last as he closes in on you.
Instead of going ahead into the control room, run back into the halls you came from. After Keyes and Cortana have their little chat, a slew of grunts will appear and rush the control room. If you're safely away, you can peek back in and snipe a few before your marines rush in to finish the job. There are a ton of grunts to go through here, so lob your frag grenades to help if you have any left.
You have one last fight before you're done with the level. There may be sniper ammo left by the control room, so stock up with whatever is around. You have to get back out into that annoying hangar one last time. Since this is the last fight of the level, use up everything you've collected. There's a pretty standard assortment of Covenant here, so you and your marines shouldn't have too much trouble. Just keep pouring on the hurt and don't let them retreat and regroup.
Once they're taken care of, you're ready to hijack your ride home. Now you can breathe a deep sigh of relief. It does get easier from here on out.