Level your Agent's Firearms skill to level four and Explosives to at least level three. You'll need Proximity Mines and the Flocket Launcher (both unlocked at Explosives level three) when defending the Comms Center Beacon.
Absorption Unit 1
The first unit is on top of the tall, blue and green building at the west end of southeast Unity Heights. Start by climbing onto the monitor to the right of the main entrance on the south side of the building. From atop the monitor, jump over to the awning above the main entrance.
Once on the awning, you can ascend to the top of the building using the sash bars on the column of tinted windows on the south side of the building. It can be difficult to make this climb because sometimes the Agent won't grab onto the bars. This can be frustrating, but just keep at it. Try pushing forward on the Right Stick when the Agent jumps up to the next bar.
Scale this building to reach Absorption Unit 1.
When you've made it onto the roof, gun down the enemy soldiers surrounding the Absorption Unit and then stand on one of the configuration platforms to start the activation process. Remain on the platform until the unit is online.
Absorption Unit 2
Ensure your Agent is equipped with an Ultra Assault Rifle and a Flocket Launcher before setting out to activate this unit. You can switch your Agent's weapons at an Agency Landing Zone or by selecting the “Extraction” option in the System section of the Intel Screen and redeploying him.
This one is on top of the curved building in the northwest corner of southeast Unity Heights. Use the rows of windows on the east side of the building to reach the roof. There are several snipers on surrounding rooftops, so quickly get onto the Absorption Unit platform to avoid their fire.
There is a Grenade Launcher-wielding enemy on the structure west of the Absorption Unit. There happens to be an explosive barrel next to him, so target the barrel and shoot it to blow him away. Activate the unit when the area is clear.
Use explosives to deconstruct the barrier blocking the power beam.
A makeshift barrier is blocking the power beam now emitting from this unit. The barrier is on top of the building across the street east of the unit. Target the barrier with your Flocket Launcher and fire a rocket to demolish it.
Absorption Unit 3
The final unit in this network is on top of one of the blue buildings at the centre of southeast Unity Heights. Use the column of windows on the north side of the building to reach the roof.
The Absorption Unit is guarded by an armoured, Turret Machine Gun-wielding Cell soldier. Take him down with grenades or your Flocket Launcher and then step onto one of the configuration platforms. There are snipers and Rocket Launcher-wielding enemies on top of the buildings to the south; take them out if they're causing you grief.
Comms Center Beacon
Before setting out, ensure your Agent is equipped with a Flocket Launcher and Proximity Mines. Both of these weapons are unlocked upon attaining Explosives level three. You can switch your Agent's weapons at an Agency Landing Zone or by selecting the “Extraction” option in the System section of the Intel Screen and redeploying him.
The Freak Lair is beneath the Comms Center at the southeast end of Unity Heights. Head to the end of the wall connected to the cylindrical structure, then move through the opening in the side of structure and drop down to the Freak Lair.
This Freak Lair is beneath the Comms Center at the southeast end of Unity Heights.
Take note of the Flocket Launcher next to the weapon crate northwest of the Beacon Drop Point marker and the Proximity Mines next to the crate east of the drop point. You'll need to use these to replenish your ammo at some point.
Stand in the Beacon Drop Point marker when ready and press the Back button to signal to the helicopter. Then, jump onto the platform northeast of the Beacon Drop Point marker and await the first wave of Freaks. Face south and focus on the group of explosive barrels there. A giant Freak will soon emerge from the ground south of the Beacon. The giant will sprint over to the explosive barrels and roar; hit the barrels with your Flocket Launcher to set them off and damage the giant.
Needless to say, the giant Freaks in this lair are the biggest threat to the Beacon. They require a ridiculous amount of explosives to bring down and will likely deal severe damage to the Beacon before you manage to make the kill.
On the upside, the only Freaks you have to worry about here other than the giants are the agile Freaks that will periodically perch themselves on the rock platform northeast of the Beacon. If you can manage to kill the two giant Freaks (a second giant will appear when the Beacon is about a quarter of the way there) before they destroy the Beacon, you can likely defend what's left of the Beacon quite easily.
Giants can severely damage the Beacon, so take them down as quickly as you can.
To bring down a giant quickly and minimize damage to the Beacon, lock on and begin firing rockets as soon as one appears. Jump around to avoid common Freaks and continue firing rockets and throwing Proximity Mines at the giant until it falls. Once you've managed to bring the beast down, focus on keeping the rock platform northeast of the Beacon clear of agile Freaks. Collect the mine and rocket ammo at the weapon crates if need be.
As soon as the second giant Freak appears, turn your attention to him and take him down the same way you did the first. You only have two giant Freaks to worry about, so once you've taken down the second, continue defending the Beacon from the agile Freaks that perch on the rock platform until the Beacon detonates.
Defending the Comms Center Beacon