This achievement will be gained once you finish the game on either "Blood and Broken Bones!" or "Death March!" difficulty levels. I recommend coupling this with the 'Walked the Path' achievement for beating the game on "Death March!" difficulty.
These difficulties are difficult at first, but will get easier as you learn and adapt.
For a full and detailed guide on completing the game on Death March difficulty go to the 'Walked the path' achievement guide (that guide will also work for Blood and Broken Bones).