In Diablo 4 Season 14, you turn a Unique into a Mythic Unique by unlocking the Mythic crafting recipe at level 70+ in Torment, then using either the Horadric Cube’s Upgrade to Mythic option or the Jeweler’s Rune Crafting option. The source I found says you need a 850+ item level Unique in the same slot, and the recipe consumes either 5 Pandemonium Fragments in the Cube or 18 specific Runes plus 3 Resplendent Sparks at the Jeweler.

What you need

  • Level 70 or higher in Torment+.
  • A Unique item with 850+ item power in the slot you want to upgrade.
  • Crafting materials for one of the two methods.

Crafting methods

Method| Requirement| Result
---|---|---
Horadric Cube| 5 Pandemonium Fragments 1| Upgrade the Unique to a Mythic Unique 1
Jeweler| 18 specific Runes + 3 Resplendent Sparks 1| Upgrade the Unique to a Mythic Unique 1

One important detail

You do not need the exact Unique named in the recipe. You only need a Unique that matches the item type or slot you want to convert.

In plain English

Farm the new Season 14 activity and materials, get a high-item-power Unique for the right slot, then use the Cube or Jeweler to convert it into Mythic tier.