The young man sacrificed the majority of Wind Mages, all to get a particular person under his control.
Even though he would have eventually received the control of the remnant of the wind tower, he didn't want to wait. Why would he wait when he could take it with his own hands?
His impatience was his biggest trait but it also allowed him to achieve the things that should have been impossible.
As for his first slave, it was the girl standing next to his mother. It was a young girl who looked to be the same age as him.
She used to be the childhood friend of the person he possessed when he Transmigrated to this world. She was his first test subject for his ability.
When he made her a slave and kept her in the coffin, she simply had to tell everyone that the girl had died at the hands of Necromancer Tower bastards, which absolved him of most of the inquiry as no one suspected him.
