Diablo III: Reaper of Souls

For this trophy you will first have to do enough bounties until you have gathered enough Rift Shard Fragments. Each rift costs 5 fragments to open. A Nephalem Rift is a random generated dungeon that will require you to slay enough monsters until the Rift Guardian spawns. Once the Rift Guardian is killed you can then close the rift in town to recieve a large bonus to experience. Rifts will drop a lot of items. Simply keep doing rifts until you have 500 monsters slain, should not be more than 1-2 rifts for this trophy. Also note that you don't have to leave as soon as you kill the boss, you may explore until you run out of dungeons. See Dashing through the Rift for a chance to knock out 2 trophies at once.