These are planetary missions involving Cerberus and mainly can be taken from Specialist Traynor standing near the Galaxy Map.
Mass Effect 3 N7 Missions Walkthrough
N7: Cerberus Lab
You should talk to Traynor to initiate this mission. You can find him in the lab in on Sanctum in the Decoris system. The waves of enemies you will face will get tougher with time so make sure that you stock up on ammo before the next wave arrives.
When Cortez goes away, you need to hold the ground on your own. Use the strategy according to the type of foe you are facing. For example, deal with the engineers before they can deploy the turrets and use biotics against the shield holders to weaken them.
You will have to defend (three to four enemy waves) until Cortez comes back, and you manage your escape.
Grissom Academy: Emergency Evacuation
After Traynor mentions the Academy, head to the Perta Nebula Cluster. Depending upon the decisions you made in Mass Effect 2 for jack, the mission can vary slightly. A couple of Cerberus soldiers waves attack you as you move on towards the objective.
You can use the generators in the room to cause some extra damage. Next, pick up the M-22 Evisceratir from the bench and then save Riley’s sister.
After you are done chatting with Jack, more enemies will arrive in entertain you. Deal with the tougher foes first and then switch to the weaker ones. After each wave, don’t forget to loot the area and also check the surrounding rooms in the area for any useful items.
Difficulty level of each next wave will be more difficult. Things will go crazy when engineers arrive with the turrets along with the guardians. If you are overran by the enemy number, then it’s always a wise option to retreat and seek cover.
In the next section, steal the Atlas for your own use from the engineer. Although the cannon requires you to stay static to fire, the weapon can come in really handy as a couple of well-placed shots can take out the enemies.
You will have to deal with a few more frantic enemy waves (stick to the basics) before you can collect your rewards at the end of the mission.
N7: Cerberus Attack
You can get access to this mission after completing Sur’kesh Deal with the first wave and then explore the area for all possible loot you can get.
After gathering the resources, hit the console for the next enemy wave. There will be a variety of foes in each enemy wave so you should diversify your style and try to deal with the tougher enemies first.
There are also multiple ways in which you can use your squad mates to draw the enemy fire so if one strategy does not work for you, shuffle the plan. After you complete the mission, you will get 50 point bonus to the Krogan First Division War Asset.
N7: Cerberus Abduction
You can initiate this mission from Traynor (after) either by helping Turians on Tuchanka or dealing with the Rachni.
The fight will be a regular wave after wave attacks with each wave tougher than the previous one. Try to hold the position where chances of being flanked by the enemy are least.
When Cortez arrives in pick you up, it’s time to loot the area for any useful items before you leave.
N7: Cerberus Fighter Base
When you are done with the problems on Tuchunka, you will be able to access this mission. There is nothing new in this mission except for the same-old horde style fights with the Cerberus.
There will be plenty of enemies in that room so don’t hesitate to use your special powers.
The last wave will be most annoying, including engineers with Turrets and the Snipers. Try to stun the turrets and take out the snipers quickly. Deal with this wave to collect your mission reward.
N7: Communication Hub
You are contacted by Admiral Hackett about an attack after the mission on Thessia. Upon return to the CIC, Specialist Traynor will alert you to the mission on Kepler Verge.
You have to save the sole survivor; Grace Sato, of the Cerberus attack at the communications facility on Ontarom in the Kepler Verge, after deactivating the hacking devices.
Completion rewards are 5 Reputation, 10,000 Credits and a War Asset; Communications Arrays. You’ll encounter Assault Troopers, Centurions, Combat Engineers, Nemesis and Phantoms.
Take cover immediately as you touch ground as troops will start converging on you soon. Cautiously eliminating enemies, proceed to find the first hacking device near a circular building.
You can also find a med-kit in the courtyard nearby and salvage 4000 credits from the red barrel near the Ariake Technologies Greaves.
Upon deactivating the device, Grace will give you coordinates for the next device and more troops will start to arrive right afterwards.
Make sure to keep moving in between deactivating devices as you might get pinned by the enemies emerging from all directions.
There is a ramp behind the device where you can find ammo and a med-kit in the central area (Upper Level) which you will surely need by now.
Salvage the red barrel near the second device for 3000 credits and find med kits near the device and in the courtyard.
After the second device, follow Grace’s directions to the third device and deactivate it to end the mission immediately.
But before you do so, make sure to find the Citadel: Cerberus Ciphers. It is a key item and you’ll find it on a computer terminal near the second device.
N7: Fuel Reactor
this mission will be added to your journal when you speak to Traynor after completion of Priority: Geth Dreadnought.
The mission is to investigate a depot that has gone offline and get it operational in order to get the allied fleet refueled.
The mission will take to planet Cyone in the Silean Nebula where soldiers have already set outpost to investigate the situation. Once you’re on the ground, meet Captain Riley for debrief.
Also, make sure to check around the area for items. You’ll find Rosenkov Materials Chestplate lying on top of some crates near the Turian named Nyrek. A Medical Treatment Plan is placed near Captain Riley that is also essential.
First off, you have to get to the fuel rod controls. But the reactor facility is draped with a green Corrosive Gas that will eat through you shield and leech your vitality upon contact.
So, your first objective is to circumvent the gas with air. Use the crane to remove the containers blocking the path to Sector A1 vent controls that’ll cleanse the air. You can now access the fuel rod controls.
Interacting with the fuel rod controls will attract a number of Husks and Marauders. The barrier engine nearby will enforce their health, be cautious of that. You’ll find 3000 credits near the controls.
After eliminating them, head to the tanks to reactivate them followed by restarting the reactor. Another 3000 credits can be found near the reactor controls.
Activating this control will call for another skirmish with the Marauders, this time with a greater number of barrier engines that you’ll have to destroy asap.
Once you’ve dealt with this clash, you’ll receive a distress call from Captain Riley, that’ll present you with a choice to either disband your team to help her or just let her be.
The final scuffle is up against a bid Brute accompanied by fellow Marauders. Kill them all to end the mission. Completing this will reward 10000 credits and a War Assets; Advanced Starship Fuel.