The Soul Splitting Secret Technique is an extremely profound and arcane special secret technique.
It allows the caster to transform other beings of the same type into their avatars, through a series of strict secret magic ceremonies. Once successful, the avatar will permanently occupy the caster's initial summoning slot.
Although ultimately classified as a Secret Technique of the Summoning School, it requires not only advanced knowledge from the Summoning School but also advanced knowledge from the Soul Faction of the Necromancy School.
The most crucial point is that the secret technique requires the casting process to be completely guided by the caster's own spiritual power. In other words, it is impossible to have other high-rank professionals cast it on their behalf.
Even as a descendant of the Olivendi Family, and presuming there is no lack of essential knowledge, it is still extremely difficult to successfully master this secret technique.