There are now enough discoveries that keeping track of them is becoming difficult, so this is our running Diablo IV Season 15 secret checklist. We will keep updating it as more solutions are found. Some entries are completely solved. Others are only partly understood. A few are currently sitting in inventories across Sanctuary while thousands of players stare at them and wonder which terrible idea Blizzard expects them to try next.
Season 15 Secret Checklist
- Solved: Hidden Diablo II Runewords
- Solved: Old Tristram and Deckard Cain's hidden journals
- Solved: Wirt's Lucky Coin
- Solved: Uber Tristram
- Solved: Hellfire Torch
- Solved: Whimsyshire and Neigh'relle
- Solved: Mefishto, Lord of Relaxation
- Solved: Godly Plate of the Whale
- Solved: Moophisto and the Bovine Sanctum
- Partly solved: Bovine armor set
- Confirmed but unsolved: Annihilus
- Under investigation: Black Mushroom
- Confirmed: Three rare secret Pit layouts
- Confirmed: Temple of Baaaaaaal
Hidden Diablo II Runewords
The secret hunt began properly when players discovered that classic Diablo II Rune combinations could be placed into appropriate base items through the Horadric Cube. Combinations such as Tal + Eth create Stealth, while considerably more expensive recipes such as Jah + Ith + Ber recreate Enigma. Blizzard did not present these as ordinary Season 15 recipes. Players found them by doing exactly what Diablo II veterans have been trained to do for decades: remembering strange combinations of tiny rocks.
We covered the full discovery in our guide to Diablo IV's hidden Season 15 Runewords. They have already become more than anniversary decorations, with players building around them, experimenting with Ancestral versions and briefly discovering that Stealth could accidentally inherit Enigma's power before Blizzard repaired the interaction.
Old Tristram, Wirt's Lucky Coin and Uber Tristram
The next major secret turned several apparently separate Season 15 systems into one enormous Diablo II reference. Players discovered ten hidden Deckard Cain journals, which eventually provide access to Old Tristram through Deckard's Memory. From there, the three Prime Evils become ingredients rather than merely bosses.
High-level Diablo, Baal and Mephisto encounters can provide Splinters of Terror, Destruction and Hatred. Put one of each into the Horadric Cube and they become Wirt's Lucky Coin. Carry that coin to the fountain in Old Tristram, make a wish and a mysterious portal can open into Uber Tristram.
Inside are Diablo, Baal and Mephisto together. Survive the family reunion and the encounter can reward the returning Hellfire Torch, now rebuilt as a powerful Mythic Charm. Our complete Uber Tristram and Hellfire Torch guide explains the whole route.
There is one warning. Some players have encountered a bug where Wirt's Lucky Coin disappears without opening the portal. Sanctuary has faced Diablo, Baal and Mephisto. Apparently faulty plumbing remains undefeated.
Whimsyshire and Neigh'relle
Season 15 also brought back Diablo III's aggressively cheerful Whimsyshire. Completing Chapter 5 of the Season Journey can reward Liquid Rainbow. Use it and the game opens the road to a world containing Cuddle Bears, Happy Clouds, Candy Jars, Unicorns and eventually the Den of Whimsy.
Waiting inside is a unicorn boss named Neigh'relle.
Yes, Blizzard really did that.
Defeating her awards the Fancy Pants title, while the area itself is one of the clearest examples of Season 15 hiding substantial content behind items that initially look like jokes. Our Whimsyshire and Neigh'relle guide covers the entire discovery.
Mefishto, Lord of Relaxation
Fishing looked suspiciously wholesome when it arrived in Diablo IV. Season 15 has repaired that problem.
Players can summon Mefishto, Lord of Relaxation, a hidden fishing boss whose route begins by catching ten Legendary or Unique fish. Mythic fish do not count, because apparently the demonic fish population has developed extremely specific dietary requirements. Transmute the ten qualifying fish in the Horadric Cube and they become a Torn Net.
With the Torn Net active, head into a hostile fishable area and start casting. Mefishto can take a considerable amount of time to appear, but eventually the fishing line can produce something requiring considerably more equipment than a landing net.
Our complete Mefishto fishing boss guide explains the process in detail.
Godly Plate of the Whale
Mefishto can drop one of Season 15's strangest legitimate Unique items: Godly Plate of the Whale. The chest armor increases normal fishing yields by 100%, effectively turning a powerful Unique equipment slot into dedicated fishing clothing.
The item is not guaranteed from every Mefishto kill, so players may need to repeat the encounter. Its purpose is gloriously narrow. It does not revolutionize Pit clearing or create a new damage multiplier. You wear it because tonight, apparently, we are fishing.
The Bovine Armor Set
The cow conspiracy is considerably larger. Season 15 contains a five-piece cosmetic Bovine armor set consisting of Head of the Bovine, Brisket of the Bovine, Foreshanks of the Bovine, Sirloin of the Bovine and Hooves of the Bovine. Every class can wear the complete outfit, presumably because dignity stopped being relevant several secrets ago.
As of September 21, community tracking has confirmed methods for three pieces. Head of the Bovine comes from a strange encounter involving a suspicious man insisting he is a cow. Sirloin of the Bovine is associated with the Cow King. Hooves of the Bovine can be obtained through fishing around the cow-related island area. The chest and gloves remain under investigation.
We are tracking those discoveries separately in our Diablo IV Bovine armor set guide, which we will update when the remaining pieces are properly reproduced.
Moophisto and the Bovine Sanctum
Then there is Moophisto, the Divine Bovine.
The current route involves the Secret Cow Level and Cow King. Players can collect Prime Ribs from the Cow King, take five to the Altar of the Heifer and gain access to the Bovine Sanctum. Another altar inside consumes five Prime Ribs and summons Moophisto.
Defeating him can reward the magnificently named Figment of Imoogination mount trophy. The Bovine Sanctum itself even contains bovine versions of useful services including a Blacksmith, Jeweler and Occultist, because apparently the cows have developed an economy while we were not looking.
Annihilus Exists, but the Route Is Still Unknown
This may be Season 15's biggest remaining mystery. Annihilus is in Diablo IV. Its item data exists, its stats are known and Blizzard has translated the famous Diablo II Small Charm into the modern Talisman system.
What nobody has convincingly demonstrated yet is how to obtain it.
That makes Annihilus particularly interesting because Hellfire Torch went through a similar phase. Players knew the item existed before they understood the hidden ritual leading to Uber Tristram. The community eventually solved that chain, which makes it increasingly difficult to dismiss Annihilus as unused data.
Our Annihilus investigation contains everything currently known. Until somebody produces a reproducible drop method, however, this one stays firmly in the unsolved column.
The Black Mushroom Is Still Suspicious
Black Mushroom has also appeared among the anniversary oddities, and longtime Diablo players immediately understand why that name attracts attention. The original Diablo used the Black Mushroom during one of its memorable side quests, making its presence in a nostalgia-heavy season unlikely to be ignored.
At the moment, however, there is no sufficiently reliable complete route connecting the Season 15 Black Mushroom to a final secret reward. That makes it exactly the sort of object we recommend keeping rather than throwing away because the tooltip looks useless.
Season 15 has already taught us what happens when players assume strange items are merely flavour text.
There Are Three Rare Secret Pit Floors
The Pit contains another quieter secret. Community examination has identified three special layouts mixed into its normal map pool: a Whimsyshire-themed floor, a cow-themed floor and a Chi'Khan or Fowl Beast-themed floor.
These do not appear to require a special trigger or particular Pit tier. They are simply extremely rare layouts inside the ordinary rotation. The loading screen does not announce that something unusual is coming either, which means the first clue may simply be realizing that your serious endgame dungeon has unexpectedly developed cows, chickens or rainbows.
The Temple of Baaaaaaal Exists Too
One of the more wonderfully stupid names attached to the anniversary hunt is the Temple of Baaaaaaal. The hidden route is connected to a secret portal in Scosglen and leads through sheep-related scenery before reaching Shepherd's Conclave.
It is not currently as mechanically important as Uber Tristram or Mefishto, but it belongs on the checklist because Season 15's secrets are not limited to chase items. Some exist because somebody at Blizzard had access to thirty years of Diablo jokes and was apparently given very little supervision.
What Is Still Missing?
The biggest confirmed question is Annihilus. The remaining Bovine armor pieces also need reproducible solutions, and Black Mushroom continues to look like the sort of object that will eventually turn out to be connected to something much larger.
There may be additional Cube recipes, secret encounters or rare portals that have not yet been properly documented. Season 15 is less than a week old, and several of its largest secrets were only solved because different players connected discoveries that initially seemed unrelated.
That means the most useful rule remains extremely simple.
Keep strange items.
Remember old Diablo recipes.
Click suspicious objects.
Fish in places where fishing appears completely unreasonable.
And when everything else fails, put it in the Horadric Cube.
Season 15 has spent thirty years preparing us for exactly this level of irresponsible experimentation.
