You’ll start this mission while talking to Udina and Anderson at the end of Citadel: Expose Saren. This is arguably the easiest of the first three missions you’ll have available to you after you’re done with your business on the Citadel, and completing this mission will get you a new companion, making it easy to recommend over Feros and Noveria.
Travel to the Artemis Tau cluster, visit the Knossos system and save your game, just in case you find you’re not up to the task of clearing Therum. When you’re ready, land on Therum, pick your squad (you won’t be able to change this until after the mission on Therum is complete) and you’ll deploy to the planet’s surface.
Therum: To the Refinery
You’ll deploy in the M35 Mako, a vehicle with considerably greater firepower and resilience than your squad has on foot. So powerful is the Mako, in fact, that on all but the highest of difficulties you’ll be able to contemptuously swat aside any enemies you run across. Even on higher difficulties, the Mako’s shields will recover if you get out of fire for a moment, and most enemy attacks of consequence are easy to dodge. You can also debilitate most enemies by simply running them over, which should destroy or knock down the foes in question, depending on their size and durability. You also have the Mako’s machine gun and turret, the former of which is incredibly accurate and capable of whittling down foes with sustained fire, while the latter deals significant damage, although it has a short cooldown between shots.
Simply put, defeating foes in the Mako basically constitutes free XP, and in the Legendary Edition, you don’t even sustain an XP penalty for remaining inside the Mako. Drive north, following the linear path ahead, turning south when you must. At first the only threat will be lava pools lining the path (a somewhat serious threat, given the Mako’s shoddy handling) but eventually a geth dropship will deploy two Geth Armatures. These quadrupedal tank-like foes can shoot discharges of energy from their heads, which will devastate you if you’re outside of the Mako, while the Mako can absorb several shots without issue. They give plenty of warning before firing, so just keep an eye on them and adjust the Mako’s position slightly when they fire to avoid their attacks.
|Secondary - Aliens: Non-Council Races / Geth: Armatures|
Destroy the amaratures and continue on to reach a narrow pass leading to the Refinery, your first stop on Therum. If you continue west you’ll find three Geth Heavy Turrets, which will fire powerful rockets at you. The Mako should be capable of taking them down, but the narrow confines and multiple opponents does make this somewhat trickier.
Take down the turrets for the XP they’re worth, but to get into the refinery you’ll need to take another approach, as the gate behind the turrets is sealed. Drive up a side passage to the north, which wraps around west to the northern end of the Refinery. You can infiltrate from this direction, but it’s not unguarded; as you drive through the pass you’ll need to defeat another Geth Heavy Turret, while on the Refinery grounds you’ll find a Geth Juggernaut, a Geth Destroyer, some Geth Shock Troopers and some Geth Rocket Troopers.
These might be difficult foes… if you weren’t in the Mako. But you are, and there’s no good reason not to just shoot them all down from the relative safety of your vehicle. The Mako can’t quit do everything, however; when the geth outside are all dispatched, disembark and note two structures to the east (near the gate outside of which the turrets lurked) and two to the north. These structures tend to house loot, gate controls, or the odd geth, so it’s what we’ll turn our attention to now:
In the northern of the two eastern buildings you’ll find and Upgrade Kit.
The southern of the two eastern buildings houses a Geth Rocket Trooper, a Storage Locker [Easy], and a “Gate Control”.
Along the southern end of the Refinery, behind a wall, you’ll find two Crates.
The eastern of the two northern buildings is empty, but you can find a Locked Crate [Easy] just south of it.
In the western of the two northern building you’ll find a Geth Shock Trooper, a Weapon Locker [Easy] and a “Gate Control”. You’ll need to open this gate to continue on.
Once the northern gate is open, get back in the Mako and get ready for another extended vehicle sequence… which mostly just means more easy XP.
Therum: To the Ruins
Drive north along the linear path from the Refinery, scrapping two Geth Armatures along the way. The two are fairly distant, and while this allows the far one to demonstrate its range, its attacks are mostly performative - unless you fall asleep, it should have no chance of hitting you at this range.
When the path turns west a geth dropship will serve as the harbinger of things to come. Shoot down two more Geth Armatures, then turn southwest to find a pass littered with Geth Rocket Troopers, behind which lurks a Geth Colossus. The Colossus is much like the Armatures, being a quadrupedal heavy weapons platform… just bigger and nastier.
Destroy them, then continue up a ramp into a tunnel, and when you emerge mow down a pair of Geth Rocket Troopers. Continue on until you find another tunnel, wherein two Geth Rocket Troopers choose to forfeit their existence, and when you emerge from this tunnel you’ll be in the “Ruins” part of Therum. Trash a Geth Trooper and two more Geth Rocket Troopers and drive on until you reach a roadblock which conveniently forces you to leave the Mako behind. The easy XP is over for this mission.
Press on through the gap in the rocks to make your way towards Liara’s Dig Site.