You will spawn with a horrible shotgun loadout, featuring weak weapons and awful passive bonuses. Slowly take the weapons you have to their small window of advantage and move up ahead.
You will be given the task to destroy a couple of generators inside a building. Take out the turrets guarding the building, run in and wreck the place.
You will sadly need to use up a lot of ammo destroying the building due to a lack of effective weapons. Feel free to use your questionably "useful" mortal grenades as well.
After destroying the generators, moving up ahead and killing some more enemies, you'll finally get a supply depo. Swap out from the terrible loadout as soon as possible and move on up ahead.
Following some dialog, you will be given the task to capture a control point that's very exposed. Either run straight up or slowly clean out the bottom floor of the building that's crawling with enemies. They will not be able to get up either way.
Once captured, I highly recommend getting up on a nearby rock with a sniper rifle and lying in wait.
A few enemies will drop on from above while also swarming the lower levels. Ignore the ones on the ground and just take out anyone that get close enough to the control point.
They will clumsily fumble towards the control point with little regards to you. Gun them down before they reach it, and if they do reach it, simply jump down and negate their hack.
Depending on how the game feels, it's completely possible that entire minutes will contain not a single enemy spawn, leaving this mission extremely easy.
Once the timer has hit 00:00 and the dialog ends, jump down and run into a nearby bunker.
Take out the nearby turrets and move up on ahead to your assassination target. No need to go back to the supply depo for a rocketlauncher, the sniper rifle does excellent hard-damage.
Take advantage of the distance in this path. Zoom in further with your sniper-rifle scope by using the scroler.
Once you reach the end of the tunnel, some more grunts will pop up outside the building.
Take out the arguably weak officers and the mission will end.