Priority: Rannoch is the third main-mission of the second Mass Effect 3 act.
It can be unlocked by completing Priority: Perseus Veil, however, before starting this mission, you should consider finishing as many N7, side, and Citadel quests as you can.
Our Mass Effect 3 Walkthrough Act 2 Priority: Rannoch is a text-guide which explains how to beat Priority: Rannoch in order to advance in the game, and eventually, complete Mass Effect 3.
The game guide reveals all points of interest, where you can find additional weapon and armor upgrades, as well as useful items that will increase your amount of credits.
“The Reaper base controlling the Geth has been located, but jamming towers prevent conventional orbital bombardment. Land on Rannoch and use a prototype targeting lase to destroy the Reaper base”
To begin Priority: Rannoch, travel to Perseus Veil, and locate Planet Rannoch. Choose the Reaper base as you landing point, and then select your crew. (Tali will be automatically selected).
Priority: Rannoch starts with a cutscene and a dialogue between Shepard and Geth VI, followed by a discussion between you and Tali. Choose your answers and you will assume control over Shepard.
Your first objective is to reach the entrance of the base. On your way you will have to fight a large number of Geth Troopers. Push forward and take them out one by one, while staying in cover.
When you reach the entrance you have to find a way to get inside the base. Jump on the pipes on the right side of the main entrance, and follow the left ladder. Stay alert because the Geth know you are there, and the will send more troops.
Go up the second ladder and advance, until you reach another one (to the left). Near it, on the ground you will find the Kassa Fabrication Gauntlets.
Pick them up and turn around. Jump over the gap between your platform and the central one. Behind a crate is the Assault Rifle Piercing Mod.
Now, turn back and climb the ladder. Follow the pipes on the left side of the platform to advance, and take out the Geth while standing on the upper platform. You have the high-ground advantage, so make sure you use it. Next, follow the large pipes to the left and advance, then follow the ladder on the right side, to reach the lower area. At the end of the platform, to the right is a green-panel door.
Behind the door, just in front of you, up on a crate you will find more ammo, and to the right, a panel. Salvage the Reaper Tech for 10.000 Credits, and then go up on the ramp, to exit.
When you go outside, firs follow the left ramp, and when you reach the end of the platform you will find the SMG Ultralight Materials Mod; then go back and advance towards your objective.
Eventually, you will see a raised square platform, and you will be attacked by more Geth Troopers. Take cover and clear the area, then search the right side of the platform for the Assault Rifle Stability Damper.
Continue to advance on the main platform and you will see another green-panel door. Next to it, on the left side, is the Geth Plasma Shotgun, and some Data you can salvage for 5.000 Credits.
Open the door and follow the corridor, but pay attention its right side.
You will find more Data that can be salvaged (10.000 Credits) and a Med Kit. When you exit the corridor turn left and advance towards the Control Panel you have to use to override the next door. Stay alert because more Geth Troopers will attack you.
Activate the panel and immediately take cover because a wave of Geth Troopers, Geth Rocket Troopers and Geth Pyro will join you. The will come through a door located on the left side of the main platform (your right, if you face the panel). Take them out then advance until you reach their spawning point, where you will see a new control panel you have to activate.
After you activate the last panel, you will be asked to use an elevator to reach a higher platform. The elevator is on the left side of the main chamber, while facing the panel. Be cautious because the elevator will bring down a Geth Prime and some troopers. Take out the Geth Prime first, then clear the area and access the lift.
In the next area, on a box in front of you is a Geth Spitfire. Pick it up and engage the Geth Prime in the central area, but keep in mind that he will be followed by two similar units. To advance you must defeat three Geth Prime units.
Stay mobile and behind cover all the time, and dont forget to use Talis powers.
NOTE: Two additional Geth Spitfire weapons can be found on the left side, and on the right side of the area.
When the last Geth Prime dies, approach towards the ledge. You will receive a laser weapon. Use it and aim the center of the base located below you. Keep the Right Trigger pulled, to complete this objective and to wake up a huge Reaper.
Watch the cutscene then turn left and sprint towards the evacuation point. The machinery will chase you and you will be asked to shoot it using the turret from your vehicle.
Since the monster cant be killed with the tiny weapon you control, it doesnt really matter where you aim. Just shoot it and watch the next cutscene.
When you assume control over your character, the Reaper will try to recover.
Quickly advance toward the end of the ledge, and using the laser system, aim the Reaper.
To kill the final boss you should use a simple strategy. First of all you should know that the laser weapon becomes available only when the Reaper fires his red beam. This beam is deadly to you, so you must avoid it at all costs. If you move around while the Reaper fires his laser, you will notice that when the beam is activated, the boss cant move it left or right.
In other words, to beat the boss, you must let him fire first, and then quickly move left or right. Fire your laser (dont forget to keep RT pulled), then wait for him to fire again. Move left or right, and shoot. The trick is to hit the boss before he can recharge and change the trajectory of his beam.
Repeat this step 5 times, and the boss will fall; however keep in mind that the last phase will be in slow motion. As soon as it starts, pull RT to complete the boss battle.
When the final Reaper dies, you will be able to start a dialogue with him. You can interrupt the conversation for more Paragon/Renegade Points.
After you complete the dialogue, you have to make a very important decision.
You must choose between the Quarians and the Geth. If you let Geth VI to upload the code, Geth VI will die as well as Tali’Zorah.
If not, you can let the Geth die and the Quarians will become much stronger, thanks to Tali’Zorah nar Rayya.
The mission ends with a cutscene, which varies based on your decision. When you return to Normandy, the Asari Councilor will ask for your presence in the Citadel.
Meet her in the Embassies area to unlock Priority: Thessia.