You are dropped on one end of "The Cauldron". You'll be moving through the level from one end to the other (just like the last time), but instead you're going the opposite direction.
You'll be immediately in view of a small group of Covenant in the lower area down the ramp. Grab the DMR by the generous ammo pile and start firing. Nobody's here but 2 Jackals and 3 Grunts, move right along.
When you approach the 2 cave arches to enter, a drop pod deploys some drops in the distance. Ignore it, since the foes are too far away to even target.
Head down the right path so you're going down the metal ramp instead of the rocky path. Then take a right through the short corridor of the small building. This way, you can get the jump on a group of Covenant(2 Elites, three Jackals) guarding the area in front of the comms array. Toss a grenade or two, then go nuts. Be careful to engage each Elite one at a time though.
When you're done with them, you're free to destroy the comms array. (It takes about one and three-fourths of an Assault Rifle clip to destroy them.) The only enemies trying to reach you now are a large group of about eight Grunts. Slaughter them.
Another load of Covenant are deployed. Attack the Elite leading the squad of Grunts first, then mop up his minions. Turn right and head up the ramp to take on the 2 Jackals and 2 Elites guarding the UNSC gear. One is using a Plasma turret, so don't move in too close.
Before picking up the IFF tag, take out the remaining Elite on another Plasma turret and any leftover stragglers. Then pick between either a Sniper Rifle or Rocket Launcher as your power weapon.
A drop pod will leave you four Elites. You can take two of them out as soon as they land with a good shot from either power weapon. Mop up the rest and head down the caves.
There's two more Elites guarding the exit, each manning a turret. Snipe them both (it should only take one shot each) and get ready for another wave.
A drop pod will deploy 6 or so tough Elites. One's got a Concussion Rifle, one's got a sword, and one's got a Fuel Rod Cannon. The Elites will take the initiative and try to rush you at once. Back up and use the Sniper Rifle/Rocket Launcher to take them out. Feel free to pick up one of the Plasma turrets from earlier as well.
When the Elites are mopped up, nothing's left but a few Grunts and Jackals. Clear them out, and the final stretch is ahead. 2 more Elites (one with a Fuel Rod Gun) will charge you up the slope, but if you still have your power weapons, it should be easy.
Approaching the last area at the top of the slope will send 2 more waves. A drop pod with 4 Elites, followed by a Grunt Jackal squad from a Phantom. Pause and wait for the Elites to arrive. Another shot from a Rocket/a few sniper bullets will take care of them. Head up the slope AFTER the Phantom leaves and you can make short work of the rest, although they can overwhelm you if just charge up recklessly.
1. This is a short level, so for the most part you won't even run out of ammo for most of your weapons as long as they aren't Promethean.
2. DON'T aim the rockets directly at the Elites! Instead, aim at the ground directly in front of them. It's easy for them to dodge the actual projectile, but nearly impossible for them to avoid a point blank explosion.
3. If you picked the Sniper Rifle instead of the Rocket, bring a good close range weapon with you like a Needler, because the speed of the Elites may quickly close the gap and move in too close.