Mass Effect 3 Priority Cerberus HQ Guide (Cronos)

If you’re pushing through Mass Effect 3 toward its finale, Priority: Cerberus Headquarters is where everything begins to lock in. This mission on Cronos Station is packed with combat encounters, optional finds, and dialogue decisions that can affect how later scenes play out—so it’s worth planning your setup before you commit.

Release-window / availability snapshot

This mission is part of the main story progression in Mass Effect 3 and is tied to endgame state. Certain outcomes reference Extended Cut content (for the Effective Military Strength threshold), while other recommendations and loot availability reference DLC like Citadel and Omega. After you start the mission, multiple optional activities are no longer available.

Category	Details
Mission name	Priority: Cerberus Headquarters
Start point / system	Horsehead Nebula → Anadius → Cronos Station
Prerequisite	Complete “Priority: Horizon”
Point of no return	Side content closes after starting this mission

Checklist: the point where side content shuts down

Priority: Cerberus Headquarters triggers the endgame sequence and is treated as the game’s point of no return. Before launching, take the warnings seriously.

Side Missions and other extras close once you begin “Priority: Cerberus Headquarters.” If you’re aiming for the highest-tier outcome and your Effective Military Strength is at least 4,000 (or 3,100 when counting Extended Cut), you’ll earn the Master and Commander Achievement/Trophy as soon as you start, and you’ll qualify for the “best” ending.

If you don’t meet that threshold, you’ll want to ensure you’ve finished everything you care about before starting—this includes DLC stories, character interactions, Side Missions, Search and Rescue, and any shopping you want to do. If you own the Citadel DLC, the guide recommends using the Armax Arsenal Arena to earn cash.

DLC
Side Missions
Search and Rescue checklist
Shopping and store planning

Unlike the first game’s structure, you do get pulled back to this moment after the credits roll, but anything you collected after this point is lost.

Reputation warning

Just before the end of “Priority: Earth,” there’s a conversation that makes reputation matter a lot. The recommendation here is to be at 100% Reputation (or very close to it) before you proceed. If you haven’t completed any DLC story content yet, that’s a fast way to push reputation up at this stage.

Mission stats and rewards

Mission rewards

Reputation: +15
Mission Credits: 55,000 credits
Found Credits: 25,000 credits
Weapon: M-37 Falcon
Armor:
- Serrice Council Greaves
- Delumcore Overlay
War Asset: This depends on how you handled the Collector Base at the end of Mass Effect 2. You get one of these mutually exclusive options:
- Reaper Brain (100 TMS)
- Reaper Heart (100 TMS)

Mission enemies

Assault Trooper
Atlas Mech
Guardian
Centurions
Cerberus Combat Engineer
Nemesis
Phantom

Travel to Cronos Station

Prerequisite: Complete “Priority: Horizon”
Location: Horsehead Nebula → Anadius → Cronos Station

After “Priority: Horizon,” you need to head to Anadius in the Horsehead Nebula. The guide estimates you’ll want about 300 units of fuel to make the trip. Dock with Cronos Station to begin the mission—this is presented as the only place you can visit within that system.

Once you dock, you’ll get a Vid-Comm check-in with Admiral Hackett. When you confirm, it becomes clear that this is the moment the final push is officially underway.

If you’re hunting for easy-to-miss dialogue, the guide suggests choosing “Let’s wait” with Admiral Hackett. There’s a small chance Traynor will mention that Hackett is available on Vid-Comm, which can unlock a one-on-one conversation. In that exchange, you can ask about “Cerberus,” then follow-ups like “And if the Illusive Man is right?”, plus topics including galactic readiness, allied forces, and Reaper progress.

When you’re ready to proceed, dock with Cronos Station using “We go now!” to launch the endgame sequence.

If you have Locked In a Serious Romance, the mission includes a scene in the Captain’s Cabin. That moment is intercut with the final dream sequence where Shepard is shown burning alongside the child. After Shepard wakes up, the plan is laid out in the War Room. The guide notes that EDI offers to come along thanks to her familiarity with Cerberus systems, while Joker is concerned about it.

Recommended loadout and squad

Squad tactics:
- EDI is treated as mandatory. Her Overload is useful for stripping the shields on this mission’s boss.
- Bringing Garrus is recommended for his Overload utility.
- If Ashley is available, her Disruptor Ammo is also described as very helpful.
Unique dialogue:
- If your romance partner is also a squad member option, bringing them can produce extra dialogue.
Shepard’s loadout:
- A Sniper Rifle helps you take out Cerberus troops at range inside this large station.
- Piercing, Shredder, or High Velocity mods are especially valued for handling Guardians.
- If you own the Omega or Citadel DLC, a Thermal Scope on your sniper or assault rifle is recommended for spotting targets through smoke effects used by Centurions and Atlas Mechs.

Escape the Hangar

After a dramatic drop into the hangar bay during the fleet bombardment, you begin the mission crouched behind the Kodiak shuttle. On the other side, Cerberus troops are already firing into your position. The guide emphasizes that Centurions and Assault Troopers will flank quickly—so thin them out early before they reach you.

Once you clear the far side of the shuttle, you’ll encounter more enemies plus an Atlas Mech entering from your left. There’s also a Nemesis sniping from the second level, so look up. With both the Atlas and the Nemesis positioned on the left side of the docking bay, you’re advised to take cover with that in mind.

The recommended flow is to eliminate troops from cover first, remove the Atlas next, and leave the Nemesis for last. If you manage to push through those threats, you’ll find two additional empty Atlas Mechs waiting on the polar ends—one on the right and one on the left—near the fighter platform.

After the last enemy goes down, you’ll hear an announcement about a security breach and the start of the Achilles Protocol. EDI explains what’s happening: the hangar will be vented. Even without an on-screen timer, the guide warns that if you don’t get EDI to an active console to halt the venting, you’ll be pulled into space and the mission fails.

To stop it, quickly climb the ladder on the left side up to where the Nemesis was, then go through the door on your right and activate the hangar bay compression controls at the window. Doing so halts the process and prevents a Critical Mission Failure.

Following the brief cutscene, reinforcements spawn on your left. Clear them out, then move down the hallway and cross to the other side of the hangar on the second level. Midway across, you’ll meet the rest of the welcome party: more Assault Troopers, Centurions, and another Nemesis. When that wave is done, continue to the far end of the catwalk and open the door.

Inside the small room, activate the Rotation Controls to aim the Cerberus fighter inward toward the hangar doors. The guide notes you can use the view prompt to confirm the effect.

Medical Station – 50 XP. Across from the Rotation Controls is a doorway leading to a small dark room. The station is on the wall inside.
PDA – 5,000 credits. In the next room, go through the following door rather than climbing the ladder. You’ll find the PDA on crates next to a red ammo box.

Return to the previous room and go down the ladder. At the bottom, turn around and go back one room. Then descend the ladder again to reach the hangar’s first floor. If you need ammunition, there should be supply around the area. When you’re ready, activate the clamp release about halfway between the ladder on the right side of the hangar and the fighter platform.

Reach the Central Lab

As shown in the cutscene, an Atlas Mech emerges from a gaping hole left by the fighter, with a handful of Assault Troopers alongside it. The guide recommends clearing the troops before they reach an unoccupied Atlas on the far left corner. As an alternative, there’s also a closer empty mech on the right—rush to it there and the enemies are easier to handle.

After you destroy the piloted Atlas, make one more ammo pass, then push through the hangar doors—or whatever remains of them.

M-37 Falcon – Located on the floor in the rubble just left of the fiery breach in the wall. Grab it immediately. If you skip it, the only other way to obtain it is via the Requisitions Terminal in the Normandy’s Cargo Bay, where it’s priced with a 10% markup.

M-37 Falcon

M-37 Falcon is described as the final weapon you can pick up in the entire game. It plays similarly to the Scorpion pistol, but the shots travel much faster. The weapon detonates when it gets close to an enemy; otherwise, it can bounce off surfaces and objects. The guide also notes that it has ammo and damage issues, but that proper mods can reduce those problems.

Take the door on the left of the fiery hole—its panel is orange, but it’s still accessible. When the cutscene ends, go down the ladder to the sublevel (as EDI suggests) and take cover right away. A few Assault Troopers and a Centurion begin attacking, and after you clear them, a Nemesis is waiting further ahead.

Once the area is safe, pick up the Med Kit just beyond the ladder before climbing back up.

Medical Station – 75 XP. If you don’t take the ladder up, continue past it to the end of the dead end. The station is on the back wall.
Terminal – 5,000 credits. This is located to the left of the Medical Station mentioned above.

Back on the main floor, EDI directs Shepard to a Cerberus Video Log terminal so you can learn more about the Lazarus Project. The guide again frames this as a reason to bring your love interest squad member, since they provide moral support during the sequence.

Serrice Council Greaves – After using the terminal, turn around and check crates for this armor piece.

Then go through the door EDI opened, walk down the hall, and drop down through the right-side opening. Vault over rubble, then take the right-hand ramp. Here you’ll run into Cerberus Combat Engineers and the irritating turrets EDI warned you about earlier. The fight is further protected by shield generators and pylons, so removing those elements makes the encounter easier.

The guide calls out that Sabotage is extremely useful here: you can hack a turret to wipe out nearby enemies. It also recommends staying away from enemy clusters to avoid being flanked, and prioritizing Engineers—especially the ones carrying large flat packs on their backs.

Once every enemy is down, climb the ladder to the upper floor. EDI needs to hack two doors this time. While she works, you should explore the rooms you can access for extra loot:

Cerberus Video Log – Far left of the orange-panel exit door. This log discusses the creation of EDI and her later counterpart, Eva Coré, whom you encountered earlier on Mars.
Cerberus Audio Log – On the room’s opposite side from the video log. It sits by an operating table covered in blood, with a PDA on top. If Jack survived Mass Effect 2 but you did not complete “Grissom Academy: Emergency Evacuation,” the PDA contains disturbing logs.
PDA – 5,000 credits. In the next room, check a table on the right-hand side.
Medical Station – 75 XP. Found on the left-hand wall among terminals.

Exit through the door EDI is working on. After Shepard confirms it’s okay for Hackett’s fleet to open fire on the station, the door becomes available. Head through it and turn right.

Pass the blue doorway, but instead take the green-panel door on your right beside a smashed window. Loot is waiting here:

Med Kit – 50 XP. As you round the left side of the room, you’ll find the kit at the bottom of the wall.
Delumcore Overlay – This body armor piece is just beyond the Med Kit on your right, before the next green-panel door. The guide labels it as the game’s final armor.
Cerberus Video Log – Go through the door to find the log. It covers Kai Leng’s meetings with the Illusive Man throughout the story.

When you’re done, return to the blue doorway and enter the next area.

The Human Reaper Remains

This room contains the leftovers of the Reaper-Human from the Collector Base at the end of the previous game. What remains here changes based on your Mass Effect 2 choices (or the imported Genesis 2 version).

If you imported a save where the Collector Base was destroyed, or you started a fresh Mass Effect 3 game, the Human Reaper Heart will be present.
If you imported a save where the Collector Base was salvaged, you’ll find the Human Reaper Brain instead.

Move forward along the catwalk to trigger the next fight. A Phantom appears near you while reinforcements arrive farther down the catwalk. Those reinforcements include Assault Troopers, more Phantoms, and a Nemesis. Sprint forward to remove the first Phantom quickly, then take cover before the Nemesis begins sniping. After that, push down the catwalk and climb the ladder.

Easter eggs

Two optional enemy appearances may occur at this point:

If you didn’t complete “Grissom Academy: Emergency Evacuation,” Jack can show up here as a Phantom enemy.
If you sold Legion to Cerberus in Mass Effect 2 for 50,000 credits, you’ll have to face that fallout here as well.

On the next floor, grab ammunition and keep climbing. Expect the same general enemy roster, just in a different layout. Continue upward until you reach the end of the catwalk section.

PDA – 5,000 credits. Before going through the door, turn around and check the far end of the catwalk.
Med Kit – 50 XP. Located next to the PDA above.

Return to the door and go through. More loot is available:

PDA – 5,000 credits. On the left side of the walkway, beside a red ammo box.
Med Kit – 50 XP. Next to the PDA.
Cerberus Video Log – Next to the PDA and Med Kit mentioned above. This log describes how the Illusive Man uses Reaper implants on his troops, linking it to the effects on Paul Grayson from the Mass Effect book line, and how that process eventually fed into his own body.

Enter the room beyond, climb the ramp, and go through the door at the top.

The Illusive Man’s Office

In this office cutscene, you’ll get another major conversation with the Illusive Man, similar in importance to the earlier exchanges on Mars and Thessia. As with those earlier moments, your choices here influence a later scene.

When the prompt appears, pick “So what is it?”, then choose one of the following:

“It’s not too late to help me” for +5 Paragon Points (Charm)
“You’re in this for yourself” for +5 Renegade Points (Intimidate)

Important: you must select the same morality option you chose during the Mars and Thessia conversations.

Next, answer either:

“You’ll never change” for +2 Paragon Points
“I can’t help you anymore” for +2 Renegade Points

The next exchange is with the Prothean VI you found on Thessia. Here, you learn the Catalyst is actually the Citadel. You can say:

“Why all the secrecy?” for +2 Paragon Points
“It’s a bit late” for +2 Renegade Points. If you use the Investigate option on the left, this changes to “This is critical information”.

Unfortunately, when Shepard tries to contact Hackett, the moment is interrupted by Kai Leng returning for a final confrontation.

The Kai Leng fight arrives in multiple waves. At the start of the first wave, Leng grapples with you. The guide instructs you to rapidly mash the MELEE ATTACK button to throw him off. Immediately, use Overload with EDI (and anyone else who has it) against Leng. After a few hits, his shields lock and you can’t meaningfully damage him. He then kneels and summons Troopers.

Although it may seem tempting to step into the pit area facing the Troopers, the guide recommends moving around the room perimeter instead. That positioning gives a better angle—especially with elevation.

Use EDI’s decoy and spread your squad to opposite sides of the room so the enemy fire is less focused. In this wave, you should be able to reduce Leng’s shields to a single bar. Keep using Overload and apply Disruptor Ammo whenever possible. The guide also highlights that a Sniper Rifle Concentration Mod is a strong tool here because it lets you slow time and land decisive shots. If your build supports melee, you can also use melee attacks.

Leng’s most dangerous move is a wave of energy that fully drops your shields. You can dodge or take cover from it, but if you get struck, be ready to use a Med Kit.

When Leng drops to one knee again, he won’t recover much before more Troopers arrive. The third wave is the biggest problem: Phantoms are difficult to handle in the trenches, so head toward the room’s sides. Keep distance between you and your squad because Phantoms are close-range threats. If you can keep firing from the sidelines, once his shield is gone you can chip away at his health. The guide notes that a single solid headshot from a Sniper Rifle can have an outsized impact.

Finally, Leng falls. In the next cutscene, you’ll get a Renegade Interrupt as Leng tries to kill Shepard. Take it to break Leng’s sword; if you ignore it, Shepard simply dodges. Either way, Shepard stabs Leng with the Omni-Blade. The guide adds that you don’t gain Renegade Points for taking the Interrupt, meaning even Paragon-focused players can choose it.

After Kai Leng is defeated, you’ll have one final exchange with the Prothean VI. When it says it’s too late, you can end it in one of two ways:

Use a Renegade Interrupt for +5 Renegade Points.
If you endure the Renegade Interrupt instead, you can trigger a Paragon Interrupt for +5 Paragon Points.

Back on the Normandy

Once the fight and final office sequence wrap up, you reunite with Anderson on Vid-Comm. The goal is to explain why the Citadel suddenly appears over Earth, right in the middle of Reaper territory—before you get one final chance to tour the Normandy.

Completing this mission gives you your final War Asset, which is a fragment of the Reaper-Human. Whether it’s the Reaper Heart or the Reaper Brain depends on your end-of-Mass Effect 2 choice. This final War Asset is what locks your Effective Military Strength for good.

Because the Citadel is now floating over Earth inside Reaper-controlled space, shopping is restricted. The guide states you can only make purchases through the Procurement Terminal in the Normandy’s Cargo Bay. It also notes that this is the last time you can use the Weapon Upgrade terminal to improve gear.

CIC: Speak with Traynor, Joker, and EDI. Joker specifically references your first conversation from the opening of Mass Effect 2.
Crew Deck: Talk with your Virmire Survivor, Liara, Garrus for +2 Reputation, and your doctor. If you didn’t romance either Garrus or Tali, Tali will be with Garrus in the Main Battery.
Engineering: Talk with Javik, Gabby, Ken, Adams, Tali (if you didn’t romance her or Garrus), and Allers.
Cargo Bay: Talk with Cortex and James.

After speaking with Allers, check your Private Terminal for the final email in the game.

If you want more Mass Effect 3 assistance, the guide points to additional pages for Legendary Edition changes, general how-to guides, key choices and consequences, a romance guide, a walkthrough, and side missions.

Mass Effect 3 Walkthrough: Priority Cerberus Headquarters on Cronos Station

Release-window / availability snapshot

Checklist: the point where side content shuts down

Reputation warning