Priority: Thessia is a Mission in Mass Effect 3. Missions serve as the main quests of the game. Completing Missions progresses the story and is the key to beating the campaign.



General Information

Previous: Priority: The Citadel III

Next: Priority: Horizon

Locations: Thessia


Video Walkthrough

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NPCs in the area









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Equipment & Upgrades

Key Items

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Priority: Thessia Full Walkthrough

Getting Started

This mission is automatically acquired after the conclusion of Priority: The Citadel III.

Liara will join you as a mandatory squadmate on this mission, leaving you with only one other slot to pick a squadmate. You will be faced with almost the entire catalogue of Reaper enemies. While Liara is great at crowd control and provides a great advantage against armored enemies, you should also consider setting your team up to be able to deal with shields and barriers as Barrier Engines and Marauders will be more prominent throughout the mission. Combat proficiencies aside, Javik is highly recommended as a squadmate. Being a Prothean, he will have plenty of insight on Asari history as well as lots of unique dialogue.

When ready, chart a course for Thessia in the Parnitha System.


The mission opens to a scene on the shuttle as Liara reveals the coordinates given by the Councilor are for the Temple of Athame, a historic location where her mother had taken her once when she was a child. She speculates there may be much more to the temple as she had found encrypted research from her mother's files, as well as some classified government funding.

Upon landing, you will see an Asari taskforce fighting a losing battle. Before speaking to Lieutenant Kurin, pick up the Umbra Visor and the supplies worth 4,500 Credits on the right side of the area. Speaking with the Lieutenant will prevent you from picking up these items so make sure to grab them beforehand. As you speak with Kurin, the Reaper forces destroy the barricade just ahead, prompting one of the soldiers to prop herself up in its place while projecting a Biotic Barrier. The Lieutenant asks you to get up on the turret on the right and help repel the enemies. You will see the Asari soldier's barrier integrity on the top right of the screen. You will need to prevent this from being depleted completely. Destroy the Barrier Engine located near the Brutes first. The real danger here are the Husks that constantly run towards the barrier. There are plenty that will jump up from the side of the bridge as well. If you focus on the Brutes in the distance, the Husks may just overwhelm the barrier with sheer numbers. Prioritize the Husks and shoot down the Brutes when you can. Once enough enemies have been killed, a cutscene triggers as Shepard convinces a reluctant and battle-weary Kurin the importance of securing the artifact for building the Prothean superweapon to end the war. Kurin orders her forces to maintain their positions and paves a way for the team to get to the temple.

When you regain control, make your way across the bridge where a large group of Marauders and Cannibals will engage you. After defeating them, head all the way to the very end of the bridge where debris seems to block your way. There is a path just behind the right wall of the building which allows passage around the wreckage. A group of Asari are taken out by a Harvester in the distance. Defeat the enemies down the steps on the left and proceed onwards. If you have a Sniper Rifle equipped, this is a prime opportunity to take out the enemies and spore pods in the distance. You should see a door at the building in the very back of the area. This is your goal. There is a Med Kit to the left of the stairs about halfway through the area and another one on the far right building's doorway. From the left Med Kit, if you follow the steps up and hug the left wall, you can find an M-560 Hydra Heavy Weapon. Note that it only has 1 shot and you may want to make it count against the group of Marauders accompanied by a Banshee just ahead. Banshees are Asari mutated by Reaper technology. They are heavily armored and have high amounts of Barriers. They perform short-range teleports around the battlefield and throw slow-moving homing projectiles at targets which can deplete shields in one hit and heavily damage health. They also perform a scream attack that covers a very large area that can knock you out of cover. Finally, if they get up close, they can perform melee attacks that stagger and deplete shields immediately or perform an instant-kill impale attack so avoid close combat at all costs. While Banshees may seem imposing, they always spawn with other Reaper forces which should be prioritized as the Banshee does not move very quickly and can easily be avoided. Other Reaper enemies may stagger you however, allowing the Banshee to get close and impale you so it's best to save them for last. For this first Banshee, proper aim with the Hydra should take it out immediately. Otherwise, maintain your distance and aim for the head.

Continue along up the ramp where the Banshee came from and follow the path to a small room where you can salvage a terminal for 7,500 Credits. Bypass the door at the end and you will come to a scene with a Reaper walking along buildings in the distance. Take out the Cannibals in the area and look for some steps on the right. Salvage the broken shotgun here for 3,000 Credits. Head out and turn around to the right and head up the ramp made of debris for a Med Kit and Shotgun High Caliber Barrel. While you were moving across this area, your squadmates should have called out an Asari sniper on the upper platform in the front. Make your way up to her and pick up the Med Kit, Sniper Rifle Concentration Mod on the ledge before her and the M-98 Widow Sniper Rifle directly to her left. Take cover next to the sniper and help her take out the Reaper forces below. Make sure you destroy the Barrier Engine on the far wall first or this encounter could take longer. When the enemies are down, take the path left and go through the broken section of the wall where the enemies were.

Follow the path up along the ledges to trigger a cutscene with a lone Asari soldier who calls for air support helping you take out a large amount of Reaper forces outside the outpost. One of the gunships is shot down by Ravagers as a Banshee arrives at the scene. When you regain control, there is a Hydra just in front of you. Take out the Barrier Engine in the far wall first then pick up the Hydra and destroy the Banshee. Once all enemies are down, continue on up the ledges ahead then turn right. Destroy the Spore Pods and pick up the Assault Rifle Extended Barrel amongst the rubble on the right. Clear out the Husks ahead and you will be faced with two Harvesters accompanied by Marauders and Ravagers. The Harvesters can be ignored if you wish as they're scripted to leave after the gunship is shot down. Focus on the ground forces instead and make sure you take out the Barrier Engine at the back. When the battle is over, continue forward and make a left. Pick up the SMG Heat Sink on the ground just outside the temple. Inspect the terminal on the right to have Liara disable the barrier.

Proceed into the temple and pick up the Med Kit on the ground to the left. The statue in the middle of the temple is the artifact you are looking for but you should inspect the other items around the large room. Liara will give you some backstory on the items and, if Javik is with you, he will provide some revelations of his own relating to the Prothean race's interactions with the Asari. Inspecting the large statue leads to a cutscene where Shepard realizes there is a Prothean Beacon hidden in the temple, to Liara's disbelief. Shepard concludes this must be how the Asari are so advanced, having had thousands of years to study the beacon while keeping it hidden from other races. A squadmate activates a nearby artifact, creating a link to the beacon. You will need to inspect the other artifacts to find more such links. The ones you want are the mural directly to the right of the statue, the manuscript to the very left, the shield at the entrance and the bust on the right side. After activating four links, the Beacon goes online, revealing a Prothean VI named Vendetta. After a long discussion regarding the Crucible and the Reapers, the VI detects an intruder revealed to be Kai Leng. The assassin brings out a holo device from which the Illusive Man appears to converse with Shepard. The delusional Cerberus leader insists on controlling the Reapers instead of destroying them. There will be opportunities to earn Paragon or Renegade points during the conversation, after which Kai Leng will attack your group.

You will not be able to kill Kai Leng. Your goal is to deplete his shields. He will periodically move to the center of the room and call on a Gunship to blind the group with a bright light and provide cover fire while he recharges. Simply maintain your distance at all times and take cover when the gunship is shooting. This simple pattern will repeat several times until you finally deplete his shield. A cutscene ends the battle as Kai Leng orders the gunship to target the temple's supports with rockets, sending Shepard crashing down below and allowing the assassin to steal the Prothean Beacon's data. The mission comes to a close as Shepard is lifted out of hole in the ground by Liara and Kai Leng makes his escape.


Back on the Normandy, Shepard reports to the Councilor about the mission's failure. Specialist Traynor will reveal she was able to track Kai Leng's shuttle to the Iera system, on the planet Horizon, unlocking the next mission Priority: Horizon.

Next Mission: Priority: Horizon


Trivia & Notes

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