N7 Missions are side missions that affect your Galaxy At War rating. N7 Missions involve Cerberus and mainly come from Specialist Traynor in the CIC. There are 6 missions total.
Cerberus Lab
How to start: Check your e-mail for messages from Admiral Hacket to receive this mission. And/or Traynor will mention about it.
Mission: Collect Reaper Artifacts and extract.
Cerberus Attack
How to start: During the Tuchanka missions same as usual
Mission: Capture the control room, restore power, and retake the control room to activate the cannons.
Cerberus Abductions
How to start: During the Attican Traverse: Krogan Team mission.
Mission: Secure the area and escort civilians to safety.
Cerberus Fighter Base
How to start:: After completion of the Priority: Tuchanka
Mission: Secure the area, disable the area defenses, and clear out remaining Cerberus soldiers.
Fuel Reactor
How to start:: After completion of the Priority: Perseus Vel
Mission: Investigate area, defeat the ambush, restart the reactor, and clean up.
Communication Hub
How to start:: After completion of Priority: Horizon.
Mission: Disable hacking devices.