User blog comment:B214/Volume 23 discussion blog/@comment-201.19.100.21-20170407184522/@comment-10330822-20170410081900

Sirzechs was in part so powerful because he inherited the POD from his mother and his father's magical talent. That in turn allowed him to bring his POD to a whole new level.

So, since Millicas's mother is Grayfia, who was Satan-Class, and his father was Sirzechs, you'd assume Millicas has the potential to be even stronger than Sirzechs.

In fact, with his mother's power, its possible that Millicas might obtain the level of control over POD that his father couldn't master in his true form.