"Protect Jack" is a mission objective in the mission "Welcome to Helios" in Borderlands: The Pre-Sequel
Walkthrough
Kill the enemies that are attacking Jack
These consist of Lost Legion Marines and Fighter Crews
Tips
If you die, you will revive in a nearby area. Go back to where Jack is and finish off the rest of the enemies.
Welcome to Helios Mission Objectives
Protect Jack
Turn in: Jack