“Follow the trail of destroyed Vex to find Tevis.”
“Track Tevis” is an objective in the mission A Ranger Lost in Destiny: The Taken King
Start on forward. You will find large piles of destroyed Vex clumped on the ground. All of them letting off some form of Void energy. There is one still standing and functioning Goblin in front of you. Destroy it or ignore it and run forward through the passage it was shooting at. As you pass the start of the passage you will hear Ghost remark on the scarring that the Nightstalker's Bow leaves behind. This will bring you forward from Campus 9 to the Endless Steps.