This difficulty is unlocked by completing the campaign on Survivor difficulty. This playthough will be slightly harder but since you played the campaign on survivor, you would already have a feel for the game and the way the go and also how to defeat certain enemies. Some areas will cause you hardship but just use your cover wisely and use first-aid kits. Always try for headshots. Don't underestimate the power of upgrading your team mates weapons. They can be fairly helpful with the right commands. You should already have the 'skill master' achievement and can spend credits on actual nanomachines you would use and to further upgrade your weapons. Doing the 2nd chapter monkey trick will help in gathering credits, remember to get to the elevator with a lot of ammo.