The most useful role is Medic. You can revive quicker and your special ability allows you to revive multiple teammates at once. You can use one player with an engineer as it will help you to kill juggernauts and vehicles quickly. Take two sentry guns and a precision strike for this mission.
If you have juggernaut available then take it to destroy the helicopters. If you don’t have it, there’s a chance that you may pick it from random crates or air drops. Precision is useful for dealing with rooftop juggernaut and sentry is useful protection both while defending the objective swarmed by suicide bombers.
If you or your squad mate brought a cruise missile, it will help to take out some of the mortars and make the crossing to the first building easier. Just move out of the house and shot down two enemy choppers.
Run faster and cover the fire to reach the next building. Counter the enemies on your way and enter into the building.
Head towards another building and go to its roof. Climb up the ladder and place a sentry gun on the edge. It will help to take out juggernaut and provide cover fire for the next objective.
When juggernaut is dead, you need one squad member to activate the next objective. They will lie prone in front while the others will provide cover.
Now you will need to complete the next objective. Clear the roof tops, move in to activate and hold the area.
For the next part of the mission, you should have 3 people posted on the inner balcony of the building to take out the approaching enemies from three directions.
Jump down, place a sentry gun and activate the objective. Stay on it to clear the enemies coming into this room.
Exit the building and grab the care package. If you can get a juggernaut suit, save it for the exfil at the end sentries are also useful to save for the exfil too.
Now you have to take the path with the best cover and move through the buildings to reach the next objective.
Enter the building and walk up to the console to active the objective.
Now you will need to find three security keys. Kill a juggernaut just outside the console room and grab the first key.
Deploy your one teammate with a sniper rifle on the roof to prevent the spawning of the enemy’s sniper.
The other three members of your squad will [ush across to take out the next two juggernauts in order to obtain keys. Kill him and pick up the second key.
If you have a cruise missile, wait for the juggernaut to leave the building. Have your teammates cover you and then take him on. Collect the third and last security key.
Head back to the console room and insert all the keys into the machine. Now you will have to go back to the building marked as chopper gunner. Use the same way to back back as you used earlier. Two members must cover your chopper gunner operator. Once the chopper is in position to cover the train, one member must go and activate the bombs.
When the bombs are armed, get everyone to the exfil, get a sentry down in this area as soon as possible, so that you can focus on taking down the chopper. By the way this is the best time to use juggernaut.
Counter all the enemies around you and must sen someone to the blue smoke to activate the exfil.
Now you can exit with exfil. You have successfully completed the mission.