Pathfinder: Kingmaker

As you progress the story, you'll get a quest for a weird well. The well is in your capital, it was located near Nok Nok in my playthrough. There's a key. Kill specific monsters to progress the quest. It is a task, so there's no need to do this, and you can choose to dedicate a backup save to this trophy if you don't want to spend a large portion of your time on this task. You can also use Dimensional Door to bypass the door. I will try to word this carefully, but if I fail, you can look it up on youtube. Use Dimension Door on the lighter part of the room beyond the magical prison door. If successful, your character should stop moving, and start casting the spell. Make sure all your party members are very close to the caster, or you'll be doing the fight, short handed. It is entirely possible to do this Side Task, fair and square, with enough time to progress your story. In fact, it will be more rewarding. Either way, have fun