Once you've retrieved the Soul Heart and located an Altar of Dark And Darker Gold Sacrifice, follow these steps:

    Prepare for the Sacrifice:

    Equip the Soul Heart in one of your utility slots. Ensure that you've cleared nearby enemies and that your team is ready to defend against potential attackers.

    Activate the Altar:

    Stand in front of the altar, face it, and press the hotkey corresponding to the slot holding the Soul Heart. This action begins the revival process, which takes approximately 20 seconds to complete.

    Pay the Price:

    Reviving a teammate isn't free—it costs the reviver 15% of their max HP. This trade-off can leave you vulnerable, so make sure your team is prepared to Darker Gold protect you during the process.