This achievement sounds hard on paper but is quite easy, with the correct operators.
How to did it,
1. Buy In the tech tree. Body Armor for -20% damage and will always fall DBNO. You will replace your drone with this
2. Loaded up any level on Moderate difficulty (Easiest,). I did New York City, Police Station solo.
3. Select Doc for his Stim pistol (+20 boosted/Blue HP). When ever you find boxes ladled Ability, use all 3 of his stims and pick up the box
4. Take each objective slow, you have 15 minutes per objective and your flashlight reveals Archeans through destroyable walls (wooden). You also are able to shoot through them aswhell
5.Even on Moderate you can die fast, go for head shots and only use unsuppressed weapons if you need to, it will draw attention to you.
This might need to retry a few times because the objectives are randomly generated.
Good luck