From GameWatcher: "Having trouble on ‘The Saboteur’ mission in Battleborn? Don’t worry, it’s not your fault. Gearbox have acknowledged the high difficulty of the mission; the developers intend on fixing ‘The Saboteur’ in the next update.
‘The Saboteur’ mission has players defending waves of enemies at specific points in the map. The mission in its current state ramps up the difficulty right near the end, sending large waves of powerful enemies directly to the objective. Randy Varnell took to the Gearbox message boards to address the situation."