However, some only show up when going near them. They show up as normal side quest markers (yellow exclamation mark) on the map. In the quest log you can see which ones you’ve already completed. There are also optional objectives to finish in a certain time limit or to not die, but the optional tasks are not needed for the trophy / achievement. You navigate through a special dungeon with lots of normal enemies and then a boss at the end. The Trials in Borderlands 3 are like mini dungeons.