Mission 7 – Exodus
Mission starts at 1:07:08
in the walkthrough video below.
This is another one where watching the video for the paths to take is very important for saving time. From the start, you’ll want to try and get a needler as soon as you can. Sometimes, one of the grunts at the start will have one, sometimes not. You don’t necessarily need it for the first group of Brutes (the ones with human hostages), but you’ll definitely want it for the 2nd area, where you have to defend the elevator before getting into it. The needler only needs to fire about 6 rounds to do a supercombine explosion and kill a Brute, which is very handy, not to mention 10 such supercombine explosions kills will net you "A Spoonful of Blamite".
Once you go up the elevator, the key shortcuts come into play, so definitely keep that in mind if you don’t want to slog through the entire mission. I take a slightly different route than RC Master (jetpacking to the highest level of one building rather than the 2nd-to-highest as he does, for safety reasons). Once you finish the mission on normal or higher, you’ll unlock the story-related achievement, "Into the Howling Dark", for finishing on normal or higher.