Item description:

ALL CHALLENGES, MODS MAXED, COLLECTIBLES

Right before last big regular enemy fight in Chapter 13 final chapter. Hold L2 and headshot a hell knight (the brute rammer with a white head) with gauss cannon. When 2-3 barons come out bring out your bfg with triangle and grab the quad dmg, kill two of them closeish together with one shot for all challenges trophy, Continue and finish mission for last doll collectible for all collectibles, you'll get last boss and complete game on any difficulty trophies too.