To get this achievement you'll need to have a regeneration equipped as your Armor Ability.
Now this achievement description isn't totally accurate, by which I mean there are other ways.
The description says near-death (no-shields) teammate, but when it unlocked for me it was when I had no shields and none of my teammates were around me. So there is a much easier way to get it.
Hope this helps, if you're going to leave a negative please leave a comment explaining why.
Happy hunting folks