You receive this quest for the hunter class by playing thru The Taken King quest line.
This is a single player quest you have to play it alone as a hunter.
This is a class specific achievement.
There are only 2 missions to play for this quest line to get the achievement.
You will be fighting level 25 vex enemies.
I did not notice a single major or ultra in either quest.
Very simple missions.
After completing the two quests and tuning them in at the tower you will earn the Nightstalker achievement and the Nightstalker subclass.