Upgrade legendary equipment in order to increase its bonuses and unlock additional slots for a jewel and a rune. There are 15 upgrade levels in total. An additional slot for a jewel unlocks at level 12, and an additional slot for a rune unlocks at level 15.

Go to the Workshop and open the Stock tab. A special marker is displayed on the icons of equipment that can be upgraded. In the case of equipment that has already been upgraded, the upgrade level is displayed.

Selecting a piece of equipment will take you to a window that shows detailed information about that piece of equipment. By hitting the "Upgrade" button, you will open the window for upgrading equipment. The latter shows the components that will be consumed in the upgrade process. If you don't have one of the required items, its icon will be highlighted in red. Selecting this icon will show a hint explaining how to obtain the required material.

This window also shows the chance for the piece of equipment to be successfully upgraded and the new values of its bonuses.

Please note: the higher the upgrade level, the lower the chance for success.

You can increase this chance closer to 100% by using the Empirite item, which can be obtained in the Dominion Ruins. The total number of all the Empirite items that you already have is displayed in the My Items tab, in the Resources section.

You can avoid using Empirite items and rely on just the base chance of success. But remember: in this case, the probability that the upgrade will be successful will be lower and a positive outcome is not guaranteed.

If the upgrade fails, you lose the consumable components and any Empirite that you used. The equipment you were trying to upgrade is left as it is, and its upgrade level doesn't change.