*Minor spoilers*
Just had a bit of a funny moment. I'll avoid giving specifics, but apparently you can get the achievement for the ancient secret of the island without doing that thing you have normally have to do. Found the temple, and noticed that I very quickly died upon entering. I'd never actually beaten the original game, so I didn't know that the temple was connected. I knew that there was a secret, and had a vague idea of that thing you have to do to get it, but I hadn't had the actual secret spoiled. As a result, I didn't know what this temple was. So because I'm ridiculously stubborn, I decided to try brute forcing my way in. Using a combination of healing spells and essence shield, I walked into the building, checked out some rooms, got murdered by spooky boys after going into one, reloaded, and instead just went over to the NPC. Talked with the NPC, got the achievement, and realized what I had done. Whoops.