Diablo 4 Season 15 Prep: What to Do Before Sept 15

Diablo 4 Season 15 is expected to start September 15, 2026, and the month between now and then is the only window where prep actually pays off. Once the season flips, most of what you’d “get ready” evaporates anyway, so the real question isn’t how to grind harder before launch, it’s which few actions survive the reset. This guide covers exactly that: the new Rebirth system, how the reworked Horadric Cube recipe should change what you do with mythics you’ve already built, and a short, clearly-flagged look at the newer PTR-only systems.

Before diving into the mechanics, here’s the version you can act on today.

Close out your Season 14 Journey

One pre-launch priority worth knocking out is finishing the Season 14 route to endgame journey chapters you haven’t claimed yet, since completing the Season 14 Journey and deciding which Eternal character to Rebirth are listed as pre-launch priorities in season-transition coverage. Claimed rewards are yours; anything still sitting unclaimed when the season ends is gone.

Decide your Rebirth character now, not on launch day

If you’ve got an Eternal character with a lot of cosmetic history attached, figure out now whether you’re converting it. Waiting until September 15 to decide means doing the gear-clearing step under time pressure, which is exactly when people accidentally lose something.

Plan your one Crafted mythic target

Because the new Horadric Cube recipe limits you to a single equipped Crafted-tag item (more on that below), decide which slot you actually want it in before you start banking materials toward it blindly.

Rebirth is the headline addition of patch 3.2.0, and it’s been one of the most requested features since launch. After over three years, Diablo 4 Season 15 is finally adding a Rebirth feature, allowing players to keep their exact characters from the Eternal realm into the Seasonal. The mechanic is straightforward in concept but the details matter, because “keeps your character” does not mean “keeps your progress.”

Your name, class, cosmetic customization, playtime, and all available cosmetics — including pets, portals, tombstones, and transmogrifications — are preserved. All inventory items and equipment equipped on your character are lost, with the system showing a warning before you confirm. Functionally, since your gear does not transfer, the leveling experience is identical either way — Rebirth is entirely a cosmetic and identity choice, not a mechanical shortcut.

Who actually benefits here: players with two or more heavily cosmetic-invested Eternal characters get the most value from Rebirth, while players who built a single standard Eternal character without much cosmetic history can safely skip it — a fresh Season 15 character starts at the same Level 1 either way.

This is the part that should change how you look at every mythic you already own, because it’s not just a new crafting option — it’s a hard constraint on how many of them you can wear at once. The new Horadric Cube recipe directly converts a chosen unique into its mythic version, and unlike the previous system, it should preserve the original item’s affixes, Tempering and Masterworking.

The catch: mythic uniques created using the powerful Horadric Cube Upgrade Direct recipe will have a Crafted tag, and you’ll only be able to equip one Crafted-tag item at a time — although that limit applies specifically to this recipe. The Upgrade Direct recipe will be more expensive than the Blacksmith or Jeweler recipes, but it’s a total 1:1 transfer of whatever you feed it in. The alternative path, the Jeweler Rune Crafting recipe, combines Resplendent Sparks and Runes and does not carry a Crafted tag — but it returns a random class-usable mythic from the chosen slot rather than a guaranteed upgrade of a specific item.

If you’ve already spent time chasing specific mythics for your build, this is worth reading against our guide to actually farming mythic uniques before you decide which one item earns the Crafted slot.

These two systems are the other big pieces of patch 3.2.0, but everything below is PTR data from the August 4–11 test window, not confirmed live-season content. Soul Splinters are new unique socketables that provide power “with a bite” — each one pairs a strong buff with a real drawback, meant to socket into jewelry. Challenge Dungeons are a new system that spawns portals in the overworld leading to boss encounters, where in Torment difficulties you can voluntarily increase the difficulty up to three Torment tiers above your current setting for better rewards. Blizzard has been explicit that the specific encounters tested on this PTR are test content and won’t be the final Season 15 versions, so treat any specific boss list or splinter count you’ve seen elsewhere as provisional. We’ve broken the full PTR content down separately in our PTR reveals versus what Blizzard held back analysis — worth reading if you want the granular list, since this section is intentionally short.

Realistically, the useful part of this checklist — clearing your Season 14 Journey, deciding on Rebirth, moving gear to the stash, and picking a Crafted-mythic target — is a few hours of account admin, not a grind. There’s no meaningful amount of in-game power you can bank ahead of a season reset, because Paragon boards, seasonal reputation, and leveling all restart regardless of what you do in August. If you skip prep entirely and just log in on September 15 to make a fresh character, you lose almost nothing except maybe an unclaimed Journey reward or two and the small convenience of not scrambling to empty a character’s bags at the last minute. Prep here is about avoiding an unforced error, not about gaining an edge — treat it as an afternoon task, not a project.

“Rebirth saves my progress”

It saves your character’s identity, not its progress. Level, gear, and Paragon points all reset to zero — only the name, appearance, cosmetics, mounts, pets, and cosmetic history carry into the season.

“The Crafted tag limits how many mythics I can wear”

It only limits Cube-upgraded mythics specifically. Mythics you find as drops or craft through the Jeweler’s Rune Crafting recipe don’t carry the tag and stack normally alongside your one Crafted item.

“PTR numbers are what launches with the season”

Blizzard has said outright that PTR encounters and balance values are test content, and BlizzCon 2026 is expected to reveal more of the season before launch. Treat anything from the August PTR window as subject to change.