The best place to earn this trophy is in the level "The Choking Ground" where you are tasked with clearing 4 portals, on the map it's the one in the SE corner "The Gory End". I advise you make a manual save just incase you don't get it on your first try, the level starts off with 4 bats which you can easily take down sometimes the next bat may be too far so hold x to shadow glide to it until the o prompt appears on screen, in total there will be 8 bats at the start and even on apocalyptic difficulty you shouldn't have many problems, as always if I've missed something please don't down vote comment why and I will explain further, thanks and good luck.