Crack in the World (Bureau)
To unlock: talk to Faulk, then Angela, then Dr Wier, then back to Faulk, and finally board the Avenger in the Engineering wing to select this mission.
You begin atop the Rio Verde dam. Go through a few rooms, enjoy the scenery. In the hallway with the sleepwalkers, one will stumble out of his cubicle and cough up a Silacoid. Whole. Yummy.
Open the door to the left to go outside for a cutscene, and combat will start immediatley afterwards with a few Outsiders. If you are fast, you might be able to kill the Psionic Commander before he retreats (if you skip the cutscene, you may get some extra pot-shots in before he splits). If not, just kill his clone for now, and take out the other aliens. Either way, in the next open area, a Gunship will appear and drop some Outsiders. Destroy the gunship, kill the aliens, and use the door to head inside.
Past the supply drop, you'll catch glimpses of the new Zudjari rank: Scouts. If you want an extra kill, go into the room at the end of the hall, then double back; a grunt will be camping in the doorway, but it's easy to get close enough for a clean headshot.
Head down the stairs to observe the Generators, and the Scout and several Phantoms hide amongst the machinery. There are 3 generators, and you must shut them all down. Shutting down the first one starts the first wave, but you can have an Engineer set up mines beforehand. Go through the small control room, then out the other door towards the second generator, where there will be a Minion Elite and Phantoms in wait. Shut down the second generator. As you approach the third generator, a Muton will drop in, along with the Scout and a Shield Commander. If you have Mind Control available, now is a good time to take the Muton. On one side of the third generator is the Laser Efficiency schematics. Shut down the third generator, and the last wave of Outsiders will come from the structure nearby, including another Minion Elite. When done, head to the top of the structure to hit the final generator deactivation button. Go through the door.
Head to the right for some Silacoid shenangians. Then the other way and down the stairs to continue. Take out the few grunts in the stairwell, and head for the flooded area, and a few more Silacoids and another Supply Drop crate.
Head on through to the Outsider construction. In the corridor of holding cells, and in the room after, take out the few scattered Grunts.
Coming out under the lake, the Avenger flies in, but the Venn gate is closed. This area is a long arena: on your end is the Endurance schematic on a console. At the far end is the console that controls the gate. A large assortment of Outsiders are here: fight your way through. Near the control console is the first Plasma Assault Canon available to you. Take it, gather ammo, and activate the Gate. You'll now need to fight your way back, as well. Once done, board the Avenger and get ready for the Zudjari homeworld.
After the cutscene, you'll land on a transport platform. Make preparations at the Supply Drop for this next gauntlet: The area is a square ring, with high ground on the left and walls on the right and on your end. As soon as you activate the terminal, the platform will move, so if you decided to bring an engineer, lay a few mines (good places: on the bridge opposite the center from the console, on the high platform on the left, and two around the openings to the 'bunker' on the right.
First, an Elite Muton will fly in from across during the cutscene. Soon, a gunship will appear from the same direction and shoot some missiles at you before dropping off some mixed Outsiders-- if you can destroy the gunship before they get off, they'll be killed, as well. A similar wave will appear from the left, landing on the raised platform, and then again from the right once you're done with that one. each time the Elite Muton flies in, you'll get a "look this way" prompt (F5 on PC) to warn you. There are a few energy packs and weapons scattered around, plus anything you can get from the aliens while fighting: this section is one you want ammo capacity in mind for.
Once done, head to the far end of the platform (there's another Kinetic Acceleration schematic here if you've missed it before), and activate the second console to open the door. To finish off the mission, head on through to see Origin...