An Orb of Regret is an item in the Path of Exile video game. It is used to upgrade the quality of an item, and can be obtained by slaying monsters, opening chests, trading with other players, or by using a vendor recipe. A vendor recipe requires a full set of 20% quality items of the same type as the item you wish to improve.

To spend an Orb of Regret, you must first identify the item you wish to upgrade. Once that is done, you can simply right-click the item and select “Use Orb of Regret”. This will upgrade the item's quality to 20%. The item will now have increased stats and a higher level requirement.

In addition, you can also combine multiple Orbs of Regret to upgrade an item to a higher quality. For example, combining two Orbs of Regret will upgrade an item to 40% quality, three will upgrade it to 60% quality, and so on.

The Orb of Regret is an incredibly useful item for Path of Exile players, allowing them to upgrade their gear and improve their characters' stats. As such, it is highly sought after and can be quite expensive. However, if you're willing to put in the time, you can obtain them for free by slaying monsters, opening chests, or trading with other players.