Diablo III: Reaper of Souls

For this trophy you will have to kill Diablo in Hardcore mode which I would recommend you do once you feel comfortable enough with your current items before you engage her. See The Prime Evil for more in depth info on Diablo. You can always back up your savegame incase you should die then simply reload it. Remember that you can always have the difficulty set to Normal to avoid any further trouble, and if you know someone who is a high level in hardcore, they can help out, but still be careful as you can still die easily.