Use a Carbine to kill the Stealth Elites on the far side. Continue into the next Hanging Gardens. They're probably firing Carbine rounds at you, which at least gives away their positions, so take them out with the weapon of your choice: Needler, Beam Rifle, Carbine, or even grenades if you throw well. Needlers, Brute Shots, or Carbines will work well on the Brutes. Things vary from there, so improvise until you get that room cleared. Take the one that goes down. 2401 argues with an assimilated Regret over the true purpose of the Halo Array.

Cortana gives you some good advice: "You might think about sitting this one out." You should have picked up a few grenades by now, and there are plenty more coming. Pick off the Jackals when their backs turned, so you don't have to worry about their shields when they are facing you later. If you're good at sniping erratically moving targets, then you can use a Beam Rifle on them. There will probably be a lonely Grunt hanging around guarding it. That allows you to take your time. There are many places in the level that require you to kill all the enemies present before a door will open for you. A particularly effective method involves a combination of grenades and one of the two weapons you're carrying. Sometimes, just one usage of this method will slay him; if not, the second try almost surely will.

Unlike the savage and single-mindedly bloodthirsty Combat and Pure Forms that precede and obey him, the Gravemind is able to analyze situations and avoid confrontation when it is necessary for the Flood's continued survival. When the Hunter raises his arm to strike, pivot around him and melee.
You'll need good timing for this. Brute Shot the swordsmen if you feel like it—there are numerous other effective ways to take care of them.

Deal with them before doing anything else. Since you just triggered the door, you might be a bit close for the Brute Shot, so aim at the middle of the swarm and empty a magazine of Carbine ammo. He was also quite logical, psychologically analyzing the duo, and trying to convince the Arbiter of the The mostly collected and impassive tone that is frequently heard from it can be justified by his implied near omniscience; his knowledge of the present and ability to accurately predict the future means that he has little reason to worry about anything. Watch out for a Fuel-Rod-wielding Grunt across the way; snipe him if you can, and take note of where he drops the Fuel Rod Gun.

Rescue the other Marines, but try to keep the ones you did rescue alive. Unlike Halo 1, the Fuel Rod won't arc like a mortar - it's more like a giant Plasma-Pistol-overload laser beam.

The Flood is a highly-infectious parasite which is released several times during Halo's story. This article is about the campaign level. Whack him for his foolishness, and get ready for three or four silver Grunts that will come around the wall at the end of the room. If you do that, a Brute will come out of the door and you'll need to take him down before proceeding. Switch to the Carbine to pick off the survivors. That limits the amount of speed-running that you can do, and makes it pointless to write a detailed speed run for the entire level. In the next room, a cloaked Elite is hanging around toward the end. Watch for hidden Brutes—occasionally the last one is injured and hiding along the path you'll be taking. There's also an Energy Sword lying there, if you're into slashing Brutes to death. It contains a couple of Jackals, several Grunts, and three Brutes. The best weapon to deal with a Brute from medium distance (which is where you'll usually be) is a Covenant Carbine. At the top of the slope, a If you have no Carbine, or even if you do and the Brutes won't stand still enough to shoot from a distance, you'll have to charge in.

The Prophet of Truth announces the retrieval of the Sacred Icon to the splintering Covenant. Headshot the Grunts, then stick and no scope the Hunters. Head back and get your Fuel Rod Gun. Get on the other side of the small Lift and assassinate enemies as they engage the Marines.
I'm sure you know this already, but I feel like it would benefit to mention, Graveminds can form wherever there is a large abundance of Flood, so there can be many, many, many Graveminds present on any give station. Melee an Elite or two to speed things up. Cortana will start talking, and you can stand there or look around or whatever, because when she's finished talking the next cut-scene begins.

Use the areas in the corners close to the throne area for cover during the first group's assault, and come out to pick them off one by one.

The Grunts are in Panic Mode, and they won't fire at you even if you fire at them.

If you've been quiet, you can sneak around and whack some of them before they wake up. Any weapon will do. Also, load your weapons first, if possible, or get off before Cortana reverses the lift. As with the others, they'll disappear if you don't grab them and stow them somewhere. Use your cunning and superior firepower to eliminate the two Kig-Yar and another Jiralhanae. Tap out the two Brute guards, then jump to the lower level and pick off enemies as they come down the small Gravity Lift. You need to kill them all before proceeding. It's your choice of cover, and watch around the edge of the structure for the Elites to fly in. Then freelance until all the enemies in the pit below you are dead. So go to the end, and exit. Now exchange the Needlers for a fresh Beam Rifle from the weapons locker on the right side of the arches. You'll have to do it the hard way—or rather, one of the hard waySome like to melee the Hunters, and the Brute Shot is a good weapon for the task. The other two levels suffer from poor design. As soon as the door starts to open, toss in a grenade, and then fire the Brute Shot into that group. Bungie wanted you to think the door is your destination, and they've made it a bit of a puzzle to figure out how to get to it. As you enter, three Brutes will come in from the door.

A third is on a There is no resistance on the ramp or the next gravity bridge, only news about Two Drones will appear in the doorway to the Mid Tower, but they will not engage you. A Minor Brute will appear on the ledge overhead, armed with a Covenant Carbine.