Advance and start your fight against the Eclipse mercenaries. I'm debating whether this counts as three separate battles or one giant fight. We'll just have to keep moving and fighting. There are mechs and mercs all along the floor. Just move from cover to cover and you'll be fine. There's not much to say in particular. There should just be grunts and a few vanguards around here. About halfway through you can take a side route along the edge of the building to flank them. I suggest just punching right through though.

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Once you make it to the end, you'll find an elevator door. Don't use it just yet. Keep going and cut to the other side of the room. At the end of the long one-way path you should find a special Viper sniper rifle. This is great for an infiltrator and good for a soldier. You should also be able to hack a terminal around here for some extra money too along with more medi-gel and some power cells.
Go back and check the wall to find a locked door. Bypass the lock and you can find a few Salarian workers. Let them out and learn that our assassin seems to have a heart of gold. Get the money from the locker and then move to the elevator.
As your squad will point out, this is kind of an attack waiting to happen. This is a good ambush position. There's one low wall facing the elevator. Tell your squad to wait there while you take up a spot further away. There's a low wall back and to the right a little bit.
When the elevator comes down, it will bring two engineers and a krogan bounty hunter. The bounty hunter should have a barrier and armor. This is why we're further back, if you were wondering. You can use your new rifle to blast through his barrier and incinerate to burn through the armor. He dies easily after that. The engineers are more of an annoyance. Just put a few rounds into them and they'll die and take their combat drones with them.
When you're ready, take the elevator up.