As your dropship descends towards Horizon, you will receive a distress call from Miranda’s sister. She will tell you that the area is under attack and ask you to leave. Land anyway. Head up the stairs in front of you and watch out as a Cerberus ship crash lands. A Reaper Harvester will quickly fly past it. Don’t let this distract you from the sniper on the ledge above. Run into the thin hallway on the right and take cover from the Nemesis. Be careful of the Phantoms, though, as they can easily sneak around you while you focus on taking out the Nemesis.
From your position behind cover, you should be able to counter-snipe the Nemesis, using Biotics to help if necessary. Order your squad-mates to guard your flanks against the Phantoms who will be rushing your position any time now. If you need to retreat from your sniping position, head up the other hall on the side and take cover. Here, you can try to hit the enemies from the other side using an Assault Rifle or something of the sort. After the battle is over, don’t forget to collect the spare Parts in the pile of rubble to the right and the Medical Station on the right wall in the next room.
A few more Cerberus ships will fly around the tower ahead, but otherwise no activity will happen in the next room. Explore for some items. Search the Log on the computer screen to watch a video of refugees looking for living quarters in Sanctuary. Search the desk to the right to find more Logs and a PDA, and examine the large window to the left to begin a unique conversation with your squad-mates. Finally, search the desk to the right by the stairs to find Inventory Logs, and head downstairs to find two more Logs next to the destroyed ships.
Continue downstairs and make a right to reach the next room. A small group of Assault Troopers will await you in this room. Take them out swiftly and keep moving forward. As you do, grab the Pistol Scope Mod off the corpse in the middle of the area and head to the left to go through a newly opened door. You will find a console to the right that you can examine to find some Salvage. Head left to proceed into the next area. If you examine the console here, you will see a video of Miranda claiming that the refugee camp is a trap. Instead of a refugee camp, this facility is actually a Cerberus indoctrination facility in disguise. Turn around and use the large white pump to drain out the pool. This will reveal a ladder leading down into a secret tunnel.
Climb down the ladder and enter the tunnel. Examine the wall to the right to find more Salvage, and grab the Rosenkov Materials Shoulder Guards from the left. Keep following the tunnel to reach a command room, of sorts, with monitors and windows everywhere. Examine the console in the center to turn on the other monitors. From here, you will be able to see into the next room, where a pack of Husks is being experimented on. Head into the other room and grab the PDA on the counter, along with the ammo if necessary. Turn to the side and examine the console here as well, which will initiate a video of Miranda (if she is still alive) running around the facility in search of her sister. Kai Leng will be in hot pursuit of her.
Run downstairs and open the door. Back up, because when the door opens a pack of Husks will attack you from the other side. Use Shockwave or Nova to knock them back and unload on them when they are stunned. Run into the next room and look to the left, where you will find more Husks. Kill them as you did the last ones and keep running down the stairs. On the way, be on the lookout for two Logs on desks. Keep following the path forward, and you will eventually reach the next big room. Reapers will swarm over this area, including highly dangerous Banshees and a deadly Ravager.
There are numerous ways to approach this battle, so if you find yourself dying a lot, try switching it up once or twice. The most straightforward approach is to press through the center of the room. Watch out for the Marauders on the upper balconies, and the Ravager to the side of the area. Take cover by the circular tables near the entrance and scope out the scene. Pick off the Marauders first, so that they can’t fire down upon you from above, and order your squad to focus on either the Banshee or the Ravager. Even through the Ravager’s powers are deadly, the Banshee is probably the most urgent threat here because of its teleportation skills and its one-hit-kill melee attacks. Once you have killed the Marauders, turn to help your squad against whichever foe you sicked them on, if the enemy is still standing. At this point, it’s probably most beneficial to kill the Banshee first. Stay on the move and use your squad to distract her while you unload all of your ammo, Biotics, and Tech her way. With the Banshee gone, you may now kill the Ravager if you haven’t yet.
Alternately, you can take a more cautious approach and sprint to the right side of the level as the enemies open fire. This will give you access to the more restricted labs area, which you can navigate by running through the various closed doors in the section. This will probably give the Marauders enough time to spring to the bottom level and join the other attackers. Hold up behind the wall with your squad and kill them as they come. When the Banshee comes into view, order your squad to focus on her. Shoot her yourself, only pausing to take out any stray Marauders who might pose a threat to you. Once the Banshee is dead, focus on the Ravager from afar. Be sure to duck away from any of his powerful projectiles during the battle.
Search the left side of the back of the arena to find Research Data and a Med Kit.
