Vetala Sorcery

The Vetala Sorcery (ヴェータラ呪術) is a magic spell that is related to the manipulation of the dead, and is grouped with the Hopping Zombie Spell and Necromancy.

Background
A vetala is a ghost-like being from Hindu mythology, which inhabits corpses and. These corpses may be used as vehicles for movement (as they no longer decay while so inhabited); but a vetala may also leave the body at will.

It is unknown what the true form of this spell is in the world of Toaru Majutsu no Index, but it can be assumed that it allows magicians to control corpses.

Kazakiri Hyouka Arc
It is referenced after Index sees Kazakiri Hyouka's leg regenerate completely after kicking Sherry Cromwell's golem down, and saving her.