Fugitive Heads

Dropped by Headless Husks in Diablo 4 Items the Headhunt zones.

These are rare spawns and may take time to farm, especially in Torment 4. Be prepared for some farming runs to collect enough Fugitive Heads.

Restless Rot

Dropped by Headrotten enemies in both the Headhunt zones and Roothold dungeons.

These enemies are somewhat common in these areas, so you'll have a better chance of collecting Restless Rot during your farming runs.

Gem Fragments

These are best obtained by farming Helltide zones, where the material drop rate is higher. Make sure you focus your efforts in these zones for efficient farming of Gem Fragments.

Step 5: 

Craft the Occult Gems

After gathering all the required materials, you'll be ready to craft your Occult Gems. The crafting process happens at Gelena's Occult Library, where you can craft three different tiers of gems:

Magic Occult Gems

These are the basic gems that provide a small boost to your Witchcraft powers or elemental resistances. Magic gems are easy to diablo 4 duriel mats craft and can be a great start for new characters or as a temporary power-up.