What About Those Tanks? Achievement in Halo: The Master Chief Collection

As a cumulative achievement, this can be done across different playthroughs of Oni Alpha Site. When the mission begins, arm the charges on the bridge and retreat to the watchtower where Mickey has set up the detonator. While positioned in this tower, but before detonating the charges, you’ll be able to spot 3 Covenant Wraiths on the opposite side of the bridge. Use your Spartan Laser (you begin the mission with this weapon) to kill each of Wraiths, and then pause your game and restart the mission. Repeat this method twice more and the achievement will be yours in just a few minutes.