How to Use the Codex of Power in Diablo IV

Salvage an unwanted Legendary at the Blacksmith to record its Aspect in the Codex of Power. If the item has a stronger roll than the Codex already stores, salvaging upgrades that entry. Then take a piece of gear you want to keep to the Occultist, choose Imprint Aspect, and select a compatible power from the Codex. Imprinting costs the resources displayed in the preview and leaves the saved Aspect available for later use.

1. Identify the power you need

An Aspect is the Legendary power shown on an item. Start by choosing one power that supports the skill or playstyle you use most. Open the Codex and look for its name. Check whether it is already unlocked and whether the stored rank is good enough to use now. If the Codex shows a dungeon source for the power, you can complete that dungeon to obtain its initial version.

When a Legendary drops, compare its ordinary stats and its Aspect separately. You can find a useful power on a piece of gear you would never equip. Likewise, a Legendary you are wearing can have a useful stat combination even when its existing power is wrong for your build. Keeping those two decisions separate makes it easier to pick what to salvage and what to imprint.

2. Salvage spare Legendaries to upgrade the Codex

1. Visit the Blacksmith with the Legendary you intend to salvage.
2. Inspect the item and check for the indicator that it unlocks or improves a Codex entry.
3. Confirm that it is a spare item you do not want to keep.
4. Salvage it, then check the Aspect in the Codex to confirm the unlock or upgrade.

The Blacksmith destroys the equipment when you salvage it. If you still need the piece in an active build, keep it equipped until you have a replacement. If you have two spare items with the same power, compare the Aspect rolls before deciding what to do with them. The Codex keeps the strongest version you have recorded, so a weaker salvage will not replace it.

3. Imprint the Aspect on gear you want to use

Go to an Occultist in a major town and open Imprint Aspect. Select the gear first, then choose the power. Picking the item first makes it easier to see which powers fit that slot. If the Aspect you want is missing from the choices, compare its allowed slots with the piece you selected.

Inspect the preview before confirming. Check the resulting power, the item's other properties, and the required materials and gold. Imprinting on a Legendary replaces the power already on that item. If you want to keep using its old power, check whether you already have that Aspect recorded before replacing it. You can use a saved Codex power again on another compatible piece after upgrading your equipment.

4. Choose when to spend materials

If you are replacing gear frequently, focus on Aspects that make a clear difference to the skills you are using right now. Imprint on a piece you expect to keep long enough to benefit from the change. You can hold on to a stronger Codex entry until you find better gear. It stays available even after you use it once.

When comparing slots, review the preview for the specific item. One slot may be more valuable for a different Aspect in your build, even if both accept the power. Put the powers that define your build in place first, then decide which remaining slots should help with damage, survival, or resource recovery.

5. Fix an unavailable Aspect or a failed imprint

If the power is missing, check whether you actually salvaged the item or only stored it. Then confirm that the Aspect appears in your Codex and that it is compatible with the gear slot. If the preview appears but you cannot finish, check the gold and material totals shown in the imprint screen.

Older guides may describe extracting an Aspect at the Occultist and keeping it as a separate consumable. For this workflow, record and upgrade powers by salvaging at the Blacksmith, then apply them from the Codex at the Occultist. That distinction helps when the menu in an old video differs from the one in your game.