I'd love a playground mode where you can go through the entire Dungeon like normal, where it doesn't count for anything or give any gains, but you could add or remove any kind of relics or marks you've already found in game to your inventory while you're playing.
Hear me out. Some of the relics have such cool and interesting, unusual, or sometimes annoying combinations. They stack in weird ways and make playing completely different. I'd love to be able to play around with all the combinations and see how they all work mix and matched. 😄