|Warning: This article is a walkthrough/guide and may contain plot spoilers.|
Note: This guide was written while playing in Normal mode. Higher difficulty levels will have different strategies.
This is section is done on the difficulty of Normal, higher levels may be different. You start by heading down the corridor and hearing gun shots below you; this is the flood fighting with the heretic’s supporters. Continue down until you reach a room with two levels, the heretic is using a hologram. Well he is speaking destroy the flood bodies with your energy sword or one found in that room, this prevents them from rising. Kill the little parasites and head through the door, you will see an elevator with flood standing there and sentinels shooting them. Kill the flood and hide from the sentinels for as long as you can, as they will to shoot the flood as with you. Destroy the containers on the elevator which will release the parasites. Once the elevator starts to move kill all the enemies no matter if they are sentinels or flood. Once at the bottom the best weapons to have would be the Energy sword and The Sentinel Beam. Head down the corridor until you get to the room with 2 levels. Don’t fight until you are shot at, once you do fight jump down and kill them all. After they are dead, there will be Heretic Elites at the on the floor above with flood on the level above that. Hide from the elites and kill the flood as they are harder to kill. There will be one more group of flood once they are heretic enemies will come from the visible door down at the end. Kill them and go through the door. You will meet some team-mates, travel up the ramp killing everything in your path. Head through the door at the top and kill the flood. No matter how much you try you cannot kill the heretic.
 Hey, Watch This!
You've found The Heretic Leader but he's escaped into a room protected by a force field. Your mission now is to climb up to the top of the station and sever the "cables" holding it up, in order to scare the Heretic Leader into leaving the room. As you climb the station you will be attacked by both Sentinels and various infected, especially Covenant Warriors. Deal with the Sentinels using any range weapon (almost all of them are quite effective), and deal with the Covenant Warriors using a combination of a Sentinel beam weapon, and your Energy Blade.
Energy Blades are very effective against Covenant Warriors in Normal Mode, and you can easily handle several enemies at once using the Energy Blade if you are careful to move around enough. Once at the top of the ramps, you have to take an elevator up to the top of the station - this is where you will find the REAL challenge in this part of the campaign.
At the top you are greeted yet again with Sentinels and Covenant Warriors: MANY of them (they come in waves). Your job up here is to sever the three huge cables arranged in a triangular fashion at each far end of the stage. Each cable that you cut will cause the platform to tilt slightly.
To cut a cable simply stand near it, and use the Energy Blade to cut across the midsection of your field of view. It takes 2-3 slashes to cut a cable but luckily the cuts do not use any of the Energy Blade's power, since you will need that to handle the waves of warriors that pop up in between severing each cable.
If you are quick, you should be able to cut all 3 cables in quick succession. If you stop to fight you will have many swarms of enemies attacking you one after the other, so you should clear off some enemies and then rush quickly to sever the next cable. The mix between fighting Sentinels and Covenant Warriors, added with the danger of falling off the platform if you run wildly, is not simple, but can be done by saving your ranged weapon ammo for the Sentinels and the Energy Blade for the warriors (one swipe of the blade is usually all it takes).
When all cables are cut the station is in freefall, but don't worry, you have unlimited time to get down and backtrack your way through the station. Apparently right as you sever all the cables, the Heretic Leader leaves his saferoom and starts making a break for the Hangar where you initially encountered Sentinels earlier!
The fight back to the hangar has no serious obstacles. The next real challenge is the Heretic Leader fight!
 Dead Or Alive...Actually, Just Dead
This segment has no major obstacles and you should be able to get through most of it. In the tight corridors keep your Energy Blade wielded, if you encounter an opponent far away its easy enough to swap to your ranged weapon, but if you are surprised by a Covenant Warrior a ranged weapon takes too long to take it down, and exposes you to more injury.
The hard part in this segment is the final boss fight, with The Heretic Leader. When you encounter him you are rewarded with a brief cutscene that features an appearance by The Oracle. Strangely, The Heretic Leader continues to behave amazingly dishonourably, almost evil, as he attacks you suddenly while you are distracted by The Oracle (this is more for story effect and has no bearing on your actual gameplay health).
 Overview of the Fight
The battle starts after the Heretic Leader creates duplicates of himself. Whether or not these duplicates are real, they pose a real threat. This battle is tough because the Leader wields dual plasma guns that appear to have a huge amount of damage. Your shields are literally depleted within seconds of exposure to their fire, so you must move quickly. The Leader also flies high up in the air and strafes around, trying to both dodge and fire at you. He's able to lead his shots in the direction of your travel so if you strafe in straight lines he will make quick work of you.
 Dealing with the duplicates/holograms
There are probably other strategies to deal with the Heretic Leader, but one that works in Normal Mode was to dispatch the hologram duplicates early in the fight. The most effective (and cheap) means of doing this is to rush forward immediately after the cutscene with your Energy Sword and slash at the holograms. You should be able to destroy both before they take flight.
 Fighting the Leader
Unfortunately, even with the holograms destroyed, the Leader is quite capable of killing you even with brief exposure to his plasma fire. One strategy that worked against him was to move to the second level of the Hangar, staying near the rear where the stairs lead up to the first column on the second floor (there are 2 sets of stairs, either one should do). This position gives you a few strategic opportunities:
- The column allows you to shield yourself from The Heretic Leader in case he depletes your shields. His flight pattern and aggressive disposition cause him to literally try and keep you in his sights at all times, reverse directions when he thinks he can catch you off guard, so the simplest way to keep the column between him and you is to run back and forth behind the column
- You are close to the stairs so you can return to the second floor if you fall down to the first floor.
- The Heretic Leader will not fly higher up to attack you, but will instead hover at just above the second floor level. This takes away part of his flight advantage, but also makes him an easier target, and also brings him within range of your Energy Sword.
The strategy you should try is to keep the column between you and him until your shields reach full strength, then with your Energy Blade equipped, watch and wait for him to fly slightly lower and relatively close to the second floor platform, then jump out and above him, slashing with your blade. 3-4 slashes, or even fewer, will defeat him. If you fail to do so, just climb back up the stairs to try again. You may also wish to using a ranged weapon to reduce his shields slightly before jumping out, but that exposes you to damage as well.
When you defeat the Heretic Leader you are treated to another very brief cutscene. This ends this portion of Arbiter's story, and you will return again to the Master Chief's story.
Credit to Redemption For writing the last two sections