Flesh Grafting

Flesh grafting is a revolutionary procedure that began as a medical treatment for withering, a condition in which a necromancer's summon (Freesoul) begins to prematurely deteriorate while the reanimation spells are still in effect. At the time of flesh grafting's discovery, necromancers were widely successful in reanimating undead puppets in the skeletal and flesh (zombie) form. With this innovative technology, necromantic society is not only able to cure the effects of withering, but also branch into wider varieties of necrotic puppetry. Flesh grafting has made possible the existence of ghouls, shrunken heads, stitchcrafts, and more.

Utility

The innovation of flesh grafting was originally developed to treat or cure withering, a condition in which a Freesoul begins to deteriorate in one or more areas of their body. For skeletons, this may involve the bones becoming brittle or -- in severe cases -- turning to dust. For fleshbound Freesouls like zombies, this can come in the form of rotted flesh or the destruction of tissue or bone, so that the affected limb/body part is no longer functional. Sometimes, the limbs fall off!
This technology has paved the way for the flourishing of other necromantic arts and new subspecies of Freesoul, including ghouls, shrunken heads, and stitchcraft creations (more than one Freesoul bound together).
Flesh grafting is only intended for use on Freesoul subjects, but there have been incidents where living persons have attempted it on themselves, whether to cure an injury or to enhance themselves in some way. This has consistently led to disastrous results and, sometimes, death.

Inventor(s)

Vesilia the Carver

Complexity

Flesh grafting can be quite complex, depending on the nature and location of the patient's withering. It requires a piece of bone or tissue that matches the afflicted area, and it requires a high level mastery of necromantic spells that work to prevent recurrence of withering at the site.

Discovery

While many renowned necromancers were working toward a successful cure for withering, flesh grafting is widely accredited to Vesilia the Carver. The story, as told by Vesilia herself, begins in her workshop, late one Drithia night in year 98. She was entertaining her daughter, Vesilia the Younger, with a pair of severed arms that she was preparing to make into clock hands.
Her assistant Freesoul, Morticio, was present in the room. He had been exhibiting signs of withering for the past few weeks, and all of Vesilia's experimental salves and spells had done nothing to revive the flesh on his arm. It was beginning to look unsightly, and he had lost almost all function in this limb. Vesilia had spent weeks, after multiple failures to find a cure, debating the heartbreaking decision to put him to final rest.
As Vesilia was preparing the final act of her shadow puppet show, a tragic moment sparked a brilliant idea. Morticio's withered arm dropped off at the elbow, crashing against the floor in an irreparable disarray. Vesilia did not want her daughter to see the beloved assistant in such a state, so she went on with the puppet show, keeping her daughter's back turned on Morticio. But, as she did so, her brilliant mind went to work. She was holding two perfectly good specimens, one of which was indeed a right arm.
When her daughter went to bed that night, Vesilia returned to her workshop and studied the remaining tissue and bone left behind in Morticio's arm. She then studied the arms she had at her disposal. She would try something brand-new and unheard of, in order to repair Morticio to good working order. 
The solution that she developed that night took several days and restless nights to get right, but she was more determined than ever. Months later, she published her findings in the Drunan Journal Of Necromantic Arts, 2nd Edition. The innovation would be called flesh grafting, and Morticio was an unliving example of its stellar success!