For this achievement, you need to enter the correct code into the computer in Second Gate of Styx. I'll provide the solution in the spoiler, with an explanation of how to find it below.
The journal by the computer gives you a code and the hint
Bringing direction to the failed and fallen, will always find its way to the living.
For this one, you'll need to convert the code from the journal into directions
. Go fail a level, then enter the code on the Mission Failed screen to get the code for the computer.