Dark Void

This is easier to do on the Battle of Ghen Crag. Don't use any bonus multipliers when attempting this trophy. As soon as you begin the mission, fly to the Weapons Locker in the center of the map. Be sure to take the Reclaimer (sniper rifle). Fly to the area with objective Alpha but stay as far away from the enemies as you can while still being able to shoot them with the Reclaimer (use the zoom by manually aiming while hovering). Kill the enemies as they spawn and attack the objective.

If any enemy begins to shoot at you, concentrate your fire on that enemy first. You must make it through the entire wave without being hit once. At some point, you will run out of ammunition. Return to the Weapons Locker and restock there to avoid enemy fire. Again, when you return, just be careful to stay out of enemy range. Also, make sure you do not collide with the environment, as this will cause damage and prevent the trophy from unlocking.

The trophy may take a few tries but it is not too difficult. The trophy will unlock as soon as you successfully complete one wave without taking damage.

Note: If you do take damage, simply kill yourself by falling then select "retry". You will begin the mission with the Reclaimer already in your inventory.