The new Castle Nathria Secret Achievement "???" added with Patch 24.4 was solved by folks from WoW Secret Finding & Collections Discord.

The reward is the Deviate Delight Card Back, made by 愚者一智 for the China Card Back Competition more than a year ago.

Creator of the achievement, Celestalon, is happy that people are enjoying the new mystery, but a bit disappointed that due to an early leak the required deck was figured out without much trouble.

Quote From Celestalon

Been seeing lots of videos and tweets of people solving the new mystery. Love it!

Finding the key deck was supposed to be more of a community-wide challenge but got skipped past pretty quick thanks in part to an unfortunate leak.

Has anyone legitimately found the deck yet tho?

Table of Contents

Previous Puzzles

How To Start the Puzzle

You will have to create a specific deck and go into Wild Ranked mode to start a game. This will enter you into the puzzle. Deck in a spoiler below, if someone wanted to figure out its content for themselves :)

Castle Nathria Secret Achievement Decklist
Castle Nathria Secret Achievement "???" Deck
A Unknown Shaman Deck created by sinti. Last updated 2 years, 2 months ago
2

Warning For Non-English Speakers

There is an ongoing bug that prevents you from starting the Puzzle if your game language is anything but English. In that case you will start a regular Wild Ranked game, not the Puzzle.

According to Celestalon, it is a known issue and it will be fixed in a later patch (source).

As a workaround, you can change the game language (not client language) via settings in battle.net, start the Puzzle in English, close the game, change the language back to your preferred one and continue with the Puzzle.

How the Puzzle Works

There are two rows of cards on the board, Locations and Suspects (minions). Your goal is to pair each Location with the correct Suspect based on the clues on them.

  • Locations start with one visible clue out of two.
  • Suspects start with one visible clue out of four.
  • Twinspell Investigate will let you reveal a clue on Location or Suspect twice a turn.
  • Hero Power Accuse will let you test (in)correct pairing of a Location with a Suspect once a turn.
  • Fireworks will go off [X] times at the end of turn based on how many correct pairs you currently have.

Tl;dr: This is basically all the information you need to finish the Puzzle, but if you want more insight, tips and tricks, continue reading.

Clues

First thing I will say about clues, understand the prompt: you need to match clues on Locations and Suspects to create a correct pair, clues are in their card text, nowhere else! Do not look for clues in card art for example.

Locations start with one visible clue out of two. Suspects start with one visible clue out of four.

Whenever a player starts the Puzzle, clues on Locations and Suspects will be randomized, so there cannot be a single, correct guide on how to solve this Puzzle. Only thing that is fixed is a clue-pair that goes together, for example Location clue "Anima Residue" corresponds with a Suspect clue "Cut on Hand". This is how you can guess which Suspect belongs to which Location. You can figure out the clue-pairs yourself, or check the list in the spoiler below.

Location-Suspect Clue Pairs
  • Anima Residue = Cut on Hand
  • Candy Wrapper = Chocolate on Fingers
  • Claw Marks = Sharp Claws
  • Crumbs = Eating a Cookie
  • Drops of Hot Sauce = Loves Spicy Food
  • Feather = Pet Bird
  • Gaudy Earring = Missing Earring
  • Grey Hairs = Greying Hair
  • Ink Smudge = Inscription Hobby
  • Lost Reading Glasses = Steamy Romance Novel
  • Mud on the Ground = Muddy Boots
  • Musky Scent = Strong Perfume
  • Scorch Marks = Singed Clothing
  • Scrap of Cloth = Torn Cloak
  • Small Flower Petals = Flower in Hair
  • Small Gloves = Petite Hands
  • Used Hankerchief = Sniffly
  • Wax Drippings = Carrying a Candle
  • White Flakes = Dry Skin
  • Wood Shavings = Whittling Knife

I would recommend investigating all Locations first because there should be higher probability that any one Suspect will have a clue matching at least some of the Locations; but don't quote me on that :)

With that said, it is entirely possible that you can have a Suspect with the one starting clue not matching any Location clue even if you investigate all Locations first.

That is still possible with even two clues revealed on a Suspect, since they have four total. For you to have an absolute guarantee to have at least one matching clue on a Suspect to any location, you might need to have three clues revealed on a certain Suspect, but that means two investigations which is an entire turn. And you might need to do that on several Suspects. That's why I recommend investigating all Locations first and trying to pair Suspects with the clues you can see and guess the rest based on Accusations, end-turn Fireworks and your chosen method of investigation (more on this later).

Investigate

You have 2 Mana for the entire Puzzle, so you can use Investigate twice a turn to reveal a clue on a Location or a Suspect.

Accuse

With Accuse, you can test one Location-Suspect pair a turn to determine whether they are correct or incorrect pairing. It doesn't matter if you target Location or Suspect.

If the pairing is correct, star-like sparkles will appear.

If the pairing is incorrect, a dark fizzle appears.

Fireworks

When you end your turn, if you have any correct Location-Suspect pairings, fireworks will appear. They will go off number of times equal to the number of your correct pairs. This will not tell you which pairs are correct, only how many are correct.

Note: Do not count into how many fireworks each individual one splits, it seems to be always 4, but do count how many times fireworks go off.

Solving the Puzzle

I like to have things organized, so I created a spreadsheet where I noted all the information I got at any given turn and also to make it visually easier for me to see the process and patterns. With Snipping Tool, I copied the cards' icons from the game for even better visual representation and used colors to further split the workflow, see below. Everyone can have a different approach, this was mine.

Start by going over the clues you see on turn one and try and match Locations with Suspects based on them to get yourself going. You have two Investigate actions and one Accuse, so make use of them to further focus your initial guesses. With the first Accuse, you will right away have one concrete piece of information if a specific pairing is a match or not. I would recommend testing the one you think is correct.

One thing I would say is not to try and test everything all at once, be methodical. You have 10 turns. It is a lot, if you are not just shooting randomly. Make a system.

You have several tools at your disposal and while Accuse and Investigate are powerful means to an end, the end-turn fireworks is the key factor in the whole process.

Double check your Suspect board position before each end-turn! When you move them around, more than one can be pushed left or right based on your actions. If you overlook an accidental misplacement, you might very well not be able to complete the Puzzle anymore based on your method of investigation and will be scratching your head why isn't your system working.

So I set up my board based on the initial clues I had - also thinking that art might be an indicator, because I didn't read instructions properly, lol! ... saw "Claw Marks", I was looking for a character with claws :D Nevertheless, at the end of the turn, two Fireworks went off. That told me 2 of the 10 pairs I tried were correct, I just didn't know which ones. I'm also fairly certain I didn't note the first Accuse I tried (I know it was incorrect, but not which pair), which could have helped me down the line.

Going into second turn, I decided to leave four Suspects where they were because I was under the impression that at least some of these four I chose were correct, still mistakenly going off by art clues as secondary indicator (besides actual clues), but in the end, that didn't matter as much as the "process of elimination" I chose. By leaving a certain number of Suspects in the same place, whatever changes I made, and those changes would either be revealed via Accuse or the end-turn fireworks, I could deduce if any new pairings were correct or not. And they were, I got three fireworks this time.

So this confirmed my suspicion that two of those four pairings I left were correct placements. To be honest, I should have started the process of elimination of those four right there, but for some reason which I no longer recall, I really strongly believed that Ara'lon in 6th position was the new 3rd correct placement and Accuse thankfully confirmed that. So that was five pairs I knew had 3 correct combinations between them, leaving the rest five to be further toyed with.

This basically split the whole board into two groups with five Locations and Suspects each, which made things easier - less possible combinations per group. I could systematically start eliminating pairs from the first group via Accuse while trying to shuffle the second group and help myself with Investigate. Noting incorrect positions of Suspects was very important to solve the second group.

I knew that since two of the OGs from the first group were 100% wrong, some of the tries in the second group had to also result in wrong matches, some of them had to belong to those two incorrect positions. Unless the two pairs would just swap, but that didn't seem likely based on the clues I had. But as a whole, I needed to keep some of the pairs incorrect, knowing they were incorrect, to see if other changes I made resulted in correct placement or not. It was all about those end-turn Fireworks, telling me if a change I made brought new correct pairs or not.

I think this was the main reason why I solved the puzzle, I intentionally kept some pairs in the wrong position, just so I could figure out placement of others. You can see that in my spreadsheet, I used Accuse on Kel'Thuzad on turn 4, but left it there just so I could test Olgra in 2nd position and Stewart in 4th, process of elimination was saying to me that one of these should be correct, but I didn't know which one, so I simply moved one of them to see if the number of Fireworks would go up or down and with that I would know with reasonable certainty which one was the correct placement.

Based on that result, and final resolution of the first group (the four originally kept pairs), I now had a pretty good idea where most of them should be placed. To be honest, I didn't expect 8 pairings to be correct, more like 6 or 7, but it just shown that my guessing game was on point and I was on the right track.

At this point I was fairly certain of 7 placements, but I've gotten 8 fireworks, so I decided to investigate twice a single Suspect of the three I was unsure of, to get as much clues on it as possible to be able to place it correctly. I thought it would be a better approach than to investigate two Suspects twice, since having only two clues on a Suspect could result in not having a single clue from its Location, but having three meant I had to have at least one matching clue guaranteed. This logic paid off and my final guess gave me the win.

I hope this guide/thought process will help you get the achievement too. I was kinda frustrated at first when I started, but as I laid out the process of investigating the clues to myself, in the end it felt like a nice accomplishment.

Tell us in the comments below if you managed to get the card back too; or if you have any questions or are stuck, feel free to ask for advice.