Mass Effect 3 Walkthrough

Mass Effect 3 Walkthrough Act 2 – Priority: Thessia

In Mass Effect 3, Priority: Thessia is the fourth mission of the second act, and it follows the events of the third main-mission, Priority: Rannoch.

Priority: Thessia is originally named Priority: Citadel, but if you visit the Citadel, after Priority: Rannoch and you talk to the Asari Councilor, the mission’s name changes.

The following Mass Effect walkthrough refers strictly to Priority: Thessia, and explains how to complete this main mission and how to advance in the game.

The purpose of the walkthrough is to help players who wish to acquire additional weapon mods, armor parts and credits.

The game guide also explains how to defeat the final boss in Priority: Thessia, what rewards players will receive and what Citadel, N7 and side-missions they can complete immediately after this important mission.


“The Asari, growing desperate as the Reapers attack their systems, have revealed an artifact that may hold the key to finding the Catalyst. Meet a scientific team at a temple on Thessia and investigate the artifact for clues.”


15.000 Credits, Experience Points


To begin Priority: Thessia, travel to Athena Nebula cluster, and land on Thessia.  Watch the cutscene and select your crew (Liara is a default member for this mission).

After you customize your weapons and crew, you will enter Thessia. During the next cutscene, you will discuss with Liara. Your conversation will increase the amount of Paragon/Renegade Points by 2.

Thessia is a war-zone, so expect multiple enemies. Your first objective is to find the Temple. When you reach the drop-off point, head forward down the ramp, and you will see some boxes on the ground.

Pick up Umbra Visor and the Supplies near the sustaining pillar, for 4500 Credits. Now turn around and talk to Lieutenant Kurin.

During this conversation the barrier protecting the outpost will fall, and you must hurry and defend the Asari. Using the mounted gun on the right side of the entrance, take out all Brutes (up to 6), and the Husks that attack the Asari.

Don’t let the human barrier fall and reload between waves. When the attack is stopped talk to Kurin again for more Paragon/Renegade Points.

Your new objective is to reach the Outpost Tykis.

Push forward and take out the Marauders that appear on the bridge. Eventually, you will reach a demolished building. Enter, then turn right and advance.

When you exit, you will have the high-ground advantage. Use it to clear the area, but expect multiple Reapers in the area, including Cannibals and Banshees.

The large courtyard features an entrance to the right. Pick up the Med Kit inside, then advance towards your objective. To the left you should see some stairs, and an Asari corpse. Near it is the Hydra Missile Launcher. If you check the next area to the left, you will find a new Med Kit in the ruins.

Now, enter the demolished building and follow the ramps up. When you reach the final ledge, look down and you should see a small fire. On the left side of the fire is a Terminal you can salvage for 7500 Credits. Bypass the next door and move forward.

In the next area, you will see some Asari snipers on the other side. Assist them and take out the Cannibals below you, then proceed through the debris. Stay on the right side of the area, and look around for a dark entrance.

To reach it, you have to go around a raised platform. Salvage the Broken Shotgun for additional credits, and then talk to the snipers.

Behind them are the Sniper Rifle Concentration Module, a Med Kit and the M-98 Widow. After you clear the area, head down and move toward Tykis.

Eventually, you will meet an Asari Soldier. If you wish to earn additional Paragon Points, you should offer your help.

After the dialogue, you will have to clear the area in front of you. If you look down you will see the Hydra Missile Launcher, which will help you very much in this situation.

Move forward and turn right when you reach the top level. Keep your eyes on the right side for the Assault Rifle Extended Barrel Mod, near a destroyed crate (on top of the crate you should see some ammo).

Continue to advance, but be very careful because the road ahead is a tough one. You will have to kill Husks, Ravagers, Marauders and two Harvesters, if you wish to proceed.

Stay in cover all the time and maintain a fair distance. Don’t forget about Liara’s Singularity power. When you reach the entrance to the temple on the left side is the SMG Heat Sink Mod.

Grab it, and then bypass the yellow control panel on the right wall.

Enter the temple and check the large statue at the end of the hall. Talk to Liara about the beacon you have found, and then examine the bust on the right side of the hall, and the manuscripts on the left side. The final connection is created by the shield at the entrance. Now, access the central beacon and watch the next cutscene, but get ready for the final boss fight, against Kai Leng.

Talk to Illusive Man, and as soon as you gain control over Shepard, take cover behind a bench. What you should know is that you won’t win this fight, and Leng will let you empty handed.

What you need to do, is to stay in cover all the time, so you can avoid the gunship behind Leng. He won’t get near you, so you don’t have to worry about that. Just fire your weapon and aim for Leng. If your shield drops, remain in cover, then fire again. When his shield drops, a new cutscene will start, showing Leng leaving with the information you obtained.

After the cutscene you will return to Normandy and talk to the Asari Councilor and Liara.

You must retrieve the data from Cerberus at all costs. Horizon Priority is now unlocked.

Talk to Specialist Traynor to unlock the N7 mission: Communication Hub.

You can now complete, Silean Nebula: Rings of Alune, Hades Nexus: Prothean Sphere, Hades Nexus: Obelisk of Karza, Dekuuna: Code of the Ancients and Dekuuna: Elcor Extraction.

Mass Effect 3 Walkthrough
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