We’re almost two months into Diablo 4’s hugely successful Season 15, yet its secrets are still keeping players guessing.
From hidden locations to unexpected rewards, Season of Hell’s Legacy has given the community plenty of reasons to explore, experiment, and share discoveries, keeping the experience fresh long after the initial launch excitement. Whether it’s the hidden town of Tristram and the Hellfire Torch, or the new Annihilus Mythic Seal, Season 15 has been a masterclass in sparking curiosity and rewarding exploration.
But for every mystery solved, another question remains—and several curious items still have players wondering whether they hold the key to something bigger. In this article we’re taking a look at some of the biggest mysteries of Season 15 that remain unsolved.
Standard of Heroes
Season of Hell’s Legacy is a tribute to longtime Diablo fans, bringing back familiar locations, enemies, items, and even music and voice acting from previous games.
Among its highlights is the return of Uber Tristram, Diablo 2’s iconic endgame encounter that pits players against all three Prime Evils and rewards victory with the coveted Hellfire Torch. But the Torch isn’t the only returning reward—the mysterious Standard of Heroes has also made its way into Diablo 4.
In Diablo 2, the last Prime Evil to fall in Uber Tristram drops both the Hellfire Torch and the Standard of Heroes. The Standard’s purpose was the subject of years of speculation. I remember dutifully picking up every one I found until I’d filled an entire stash, convinced they’d come in handy someday.
They never did. In Diablo 2, the Standard was simply proof that you’d beaten Uber Tristram. That may be all it means in Diablo 4, too, but whether it has a hidden use this time around remains an open question.
Chat Gem
The nods to Diablo 2 don’t stop there. Longtime players may remember clicking the mysterious Chat Gem in the Battle.net lobby and wondering what they’d just activated. In Diablo 4’s Season 15, the Chat Gem returns as a Mythic gem you can actually socket into your gear.
The Chat Gem has a long history of serving as a running joke in Diablo 2. Once clicked in the multiplayer chat lobby, it would repeatedly post “Gem Activated” and “Gem Deactivated” inside the chat. After enough time, a “Perfect Gem Activated” message would appear, sparking even more speculation about its purpose. On very rare occasions, it would even moo.
Some players were convinced that activating a Perfect Gem before starting a game meant they’d find more gems or encounter more Gem Shrines. Neither theory ever panned out, but Blizzard was happy to keep the joke going, saying the Chat Gem “is working correctly and has more than exceeded our expectations.”
Of course, the Gem has never had a real purpose.
In Diablo 4, socketing the Chat Gem into a piece of gear brings those messages back. They appear in chat from time to time, including “Perfect Gem Activated” and the occasional moo. The gem can also post strings of numbers, adding to the mystery.
To get your hands on this item, keep an eye out for The Cornerstone of the World, a rare Waking Nightmare portal that can appear in the open world. Helltides are a good place to look, though finding the portal doesn’t guarantee a Chat Gem drop.
As with the Standard of Heroes, no one has confirmed a use for the Chat Gem beyond what you can see in chat. Whether those numbers mean anything is still an open question.
Black Mushroom
The Black Mushroom takes us back to the original Diablo. On level nine of the Labyrinth, the first floor of the Caves, players could find a Fungal Tome and bring it to Adria to begin the Black Mushroom quest.
The quest has humorous undertones. Once Adria sends you back into the Caves to find the mushroom, this prompts one of the Warrior’s more memorable lines: “Now that’s one big mushroom.” You can hear it in this clip from YouTuber Kris Absolution:
The Black Mushroom returned in Diablo 3 as one of the rare ingredients needed to craft the Staff of Herding, which granted access to Whimsyshire.
In Diablo 4, the Black Mushroom returns as a consumable. If you’re hunting for one, try running Waking Nightmares with narrow passages, such as the Forgotten Tower, Halls of the Blind, or the Den of Evil. You can repeat these dungeons with their corresponding sigils. Keep an eye out for a small patch of dark mushrooms and interact with it if you spot one.
Eating the Black Mushroom makes your character vomit. Whether it serves any purpose beyond making you immediately regret eating it remains a mystery.
Map of the Stars
The last item on our list might be Season 15’s most intriguing mystery: the Map of the Stars.
The Map of the Stars is another item that has a long history in Diablo franchise, but even longtime fans may not have heard of it before Diablo 4 paid homage to it. The map was part of a quest of the same name that was cut from the original Diablo.
In the planned quest, players would have found the map after defeating Archbishop Lazarus, the game’s penultimate boss. After showing it to Deckard Cain, they would have had exactly one hour to defeat Diablo before he regained his full power.
The Map of the Stars later appeared in Diablo 3 as part of The Darkening of Tristram, an annual event held every January.
Diablo 4 brings the map back once again. Season 15 continues the Secret Cow Level saga, but players also uncovered a Secret Sheep Level early in the season. Reaching it takes several steps, which we cover in our Secret Sheep Level guide.
The red portal inside the Forlorn Hovel in Scosglen takes players to the Temple of Baaaaaaal, a burning temple filled with sheep. Inside, players will find a Dead Cultist. Clicking on the corpse drops the map.
So far, the map has no known use. What sets it apart is the message players see when they try to use it: “You can’t use this now, or here.” That wording hints that the map might work in a particular place, at a later time, or perhaps even in a future season.
Of all the items we’ve covered, the Map of the Stars seems the most likely to hold a secret we’ve yet to uncover.
