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Defend Energy Reactor is one of the final missions in Armored Core 3.

Defend Energy Reactor

Path to the energy reactor.


Requester: Union

Advance: 0

Upon success: 67000

Operation Area: Energy Reactor

Enemy Forces: Unknown

Objective: Defend the energy reactor

Operation Code: Crying Baby

Client Name: Union

Place Name: Energy Reactor

Start Time: 13:00

Security Level: 9

Estimated Success Rate: 9%

Recommended Raven Rank: S


Raven, Controller forces have succeeded in occupying the energy reactor!

Their objective is unclear, but if the reactor is destroyed it will set off a chain reaction causing extensive damage throughout the city.

To make matters worse, the facility's security system has been activated. In order to reach the core, you'll have to bypass both gun emplacements and energy shields.

We're running out of time. Good luck.



Reactor Announcement:Intruder detected. Activating security system.

Laine Meyers:Receiving mission update. Enemy forces have already reached the reactor’s core. There’s no time to waste!

Reactor Announcement:Anomaly detected. Core temperature rising.

Laine Meyers:Something is wrong! Hurry!!

Reactor Announcement:Warning, maximum containment levels exceeded.

Laine Meyers:Reactor core destroyed! Mission failed.


This is one of the more difficult missions in the game, packed full of hazards and unfavorable conditions. Equip either a well-armored AC to endure the laser turrets, or an agile one to bypass the shields quickly.

When you start the mission, your path will be temporarily blocked by a hall of energy shields. While you can pass through them without stopping, you will sustain a fair amount of damage doing so. After a moment, the shields will retract and let you pass, but at the same time a major danger will present itself. When you hear/see the announcement "Intruder detected! Activating security system!", immediately advance forward and retreat into one of the gaps you're close to in order to avoid the upcoming energy blast fired from the end of the hall. Being hit by this attack may cost you 3000+ AP, which may cripple your chances of completing the mission. Your goal is to make your way to the end and destroy the wall while sustaining as little damage as possible.

The final obstacle in this part are the ceiling turrets that await to pester you while the shields are up. You might shoot them down (a task best delegated to EO), but that is not going to help much as they appear both in front and behind, and worse yet they respawn - hiding in the gaps might be preferable provided that you can move fast enough between them when the shields are down and the deterrence blast is impending. Alternatively, blast off the two turrets in front as soon as they appear and put yourself before the next energy shield - this way you the turrets behind you will not be able to reach you anymore. Remember that as you progress down the hall, the energy blast will meet you sooner - memorize the timing of the launch and take cover at all costs. When it comes to the wall itself, in order to tear it down you have to not to hit it enough, but hit it dead center, where the muzzle of the sequential energy cannon is marked as your target. If you aim well enough, a single small rocket will suffice. Once the reactor barrier is destroyed, you will be transported right into the reactor chamber, skipping the remainder of the hallway.

Once the wall is brought down, you will be faced with a quad-leg Controller AC using the POWER laser weapon arms which do a considerable amount of damage. It will combine the POWER laser cannons with the EO attacks and back pulse cannon, creating a highly dangerous volume of beams coming your way. A well-armored AC with good energy defense can stave off the energy-eccentric AC, while a maneuverable one can dodge its attacks. Fortunately, this Controller AC is not the best at turning after you, and blindsiding it is vital in order to make its weapons lose track of you. And while it is not too tough itself, you are not going to last long fighting it head on if you do not come in a very durable AC, and such one might have trouble to keep up with the opponent in turn. Moreover, you must be careful as not only you are on a time limit, but that the energy reactor can sustain damage from your crossfire, so do not rely on it for cover lest it gets blown up as a result of the fight. All of these factors combined suggest to focus on destroying the Controller AC as fast as you can, before it can do serious damage to you or the reactor. Bring some heavy weapons and flank the AC for best results.

Ultimately, this fight cannot take long - preferably, you should throw down as much fire at the Controller AC as soon as possible, then get out of its way as it tries to rush you. Staying away from its front is paramount to avoid major harm from its multiple energy weapons. Keep flanking it and hide behind the generator when needed. However, the enemy AC may keep firing at the generator with its EO while your are in cover, so do not let it damage the generator for too long. Lastly, to avoid collateral damage, try to only fire at the opponent when your line of sight is not colliding with the generator. As long as you do not get cornered and can keep scoring clean shots, the mission will be complete before long.

To earn S Rank in this mission, complete it as quickly as possible and stay above 50% AP.


  • Although there is no visible timer, this is de facto a mission on time limit.
  • The fight against the Controller Agent is much alike the confrontation against Chain Impact back in Destroy the AC mission, only significantly harder due to the "upgraded" enemy quadruped AC, and the additional objective of protecting the reactor.