I had a great time doing the Alterac Valley mystery puzzles! It took me several hours to get through, but the guide on Hearthstone Top Decks was extremely helpful, and it was a fun adventure. I printed out all the maps and used a pin to keep track of my location and was very cautious so I could succeed on the first try. It’s absolutely bonkers how involved the quest is, but that makes the achievement that much more satisfying, and you can do it without needing to collect any particular cards first.