Collector Base

The Collector base is a massive space station located in the galactic core near the outer edge of a black hole. Home to countless Collectors, Seeker swarms, and Collector controlled Husks, it also houses the Collector General, all of which are working for Harbinger. It can only be reached via the Omega 4 Relay and is surrounded by a vast debris field which several Oculus hide in. Able to survive being so close to a black hole due to what Commander Shepard presumes is Reaper technology, it keeps at least one Collector Cruiser docked with it, proving its size due to the way that the base dwarfs the cruiser. It has the same almost organic interior as the Collector Cruisers.

After Shepard discovered a way to safely travel through the Omega 4 Relay with a mission to stop the Collector attacks on human colonies, Shepard took the team to the base aboard the SSV Normandy SR-2 where they made it through the defences surrounding the station, even managing to destroy a Collector Cruiser. However the explosion caused by the destruction of the cruiser caused the Normandy to crash on the surface of the station, though it remained undetected due to either the base's external sensors being blinded by the explosion or lacking a security system, this flaw possibly true due to Collector overconfidence in the idea that nobody could overcome their defences. Depending on the upgrades Shepard has purchased for the SSV Normandy SR-2, up to three squadmates may be killed during the impact, depending on who is in Shepard's party at the time.

Once on the station, Shepard and the team decided to destroy the station by overloading the critical systems from the main control center. Getting to it would mean going through a central chamber where the colonists that had been abducted were presumed to be if they were still alive. In order to divide the Collectors, the team decided to split up, each team taking one of the two main routes to the central chamber. However both routes were blocked by doors which needed to be opened from the other side, so a member of the team was assigned to climb through a ventilation shaft which led past the doors so the security system could be overridden and the doors could be opened, with the two teams fighting up to the doors providing a distraction for the Collectors.

Once the team had reunited past the doors, fighting off enemy forces the whole time and sealing the doors behind them, they found themselves in the central chamber and faced with the sight of numerous abductees in pods. After realising that they were still alive and watching one of the people in the pods melted down and killed, the team hurried to free people from the remaining near by pods, recovering Doctor Chakwas and a couple of other Normandy crew members. Discovering that the colonists and other members of the Normandy crew had been turned into raw genetic material and pumped through a tube network for an unknown reason, Shepard had Chakwas and the other Normandy survivors return to the Normandy while the team decided to move on to the main control room which was also where the tubes were leading. The route was also blocked by a security door but there was another route, though it was filled with Seeker swarms. To repel the swarms, a Biotic member of the team would project a defence field and take a small team led by Shepard round to the other side of the security door which the rest of the team fights its way to.

Shepard's team fights its way to the security door and opens it so the diversion team can pass through, sealing it behind them. EDI informs Shepard that some near by platforms lead to the main control console which can be used to overload the systems and destroy the base. However Collectors begin massing outside the security door, trying to open it and get to the team. Shepard takes two squad mates to aid in reaching the control console while the rest of the team is left behind to keep the Collectors from making it through the door. Shepard's group is able to fight its way across a number of platforms before reaching the control room and discovering what the tubes are pumping the human material into: a Human-Reaper. After dealing with some more Collectors and destroying the tubes holding the Human-Reaper over a large pit, the construct falls and is apparently destroyed. As Shepard orders the team holding back the Collectors at the door to return to the Normandy and gets ready to set the overload, a message comes in from the Illusive Man. He asks Shepard to set the reactor to give off a radiation pulse instead of setting it to overload. This way, instead of the station being destroyed, the Collectors in the base would be killed and the technology left intact for Cerberus to use against the Reapers. Shepard has doubts about this but the Illusive Man tries to convince Shepard to see things his way. In the end, Shepard makes the decision and sets the reactor. However, the Human-Reaper climbs out of the pit and engages Shepard and the two squad mates. After the Human-Reaper is destroyed once and for all, Shepard hurries back to the Normandy, chased by Seeker swarms and Collectors. The Normandy races away from the base as the countdown reaches zero, Harbinger vows to carry on ss plans, and the Collectors are killed.

Depending on the choice made by the player at the end of Mass Effect 2, the Collector base is either preserved for Cerberus, or destroyed. If the player destroyed the Collector base, a cutscene would happen with the Illusive Man, and the star behind him is blue (red if the player decided to save the base for Cerberus, which is the renegade choice), indicating that the player's choice could decide the whether the Illusive Man is paragon or renegade.