Knight Tatru's Ointment (5e Equipment)
From D&D Wiki
When the end of a hand or foot is placed within this jar of ointment, any missing digits or toes on that hand or foot are regrown in a fully healed version of the state they were in before being cut-off. All the penalties given to the character to account for this missing piece are no longer in effect, and they heal by the amount of their maximum hit points they lost with the injury. 1/10th of a jar can be used to heal a single toe or digit, and one entire jar can be used for healing a hand or foot, but the amount required to heal larger missing limbs (such as an entire arm) grows exponentially with the size of the missing flesh, making further use impractical. In addition, the item can only replace skin, blood, skeletal muscle, cartilage and bone, and therefore cannot be used to heal internal organs other than the aforementioned.