After you meet your father(mahrlok), talk to Ardek again. Choose to go after the remaining foremen. When you clear the final area, choose to spare the orc for this achievement. Keep in mind that if you spare him, you will not be able to get the "No quarter" achievement, so make a save file beforehand to collect both. You must leave the orc alive if you want to get "Guidance counselor".(credit to DKsDragon's trophy guide map)