The Four Artificial Spirits from the original Monster Girl Quest created by Promestein makes a return in form of a skill.
Overview
In the original timeline, these four spirits were mass produced by Promestein and used to power up monsters enhancing their skills and abilities in hopes to defeat Hero Luka. You can get these Artificial Spirits through a certain Job.
Trivia
It is unknown whether the alternate version of Promestein re-created them in this timeline and her location is currently not known whether she is traveling around, but rumors of a person with a coat is traveling around.