Millennia and millennia
Kayden estimated that he would only be at half the strength he had accumulated if he had let normal mana be part of his advancement. It was a huge difference in strength, even more so with the jewelry on his head. The jewel in the center of his head was different from the other four, as the one in the center was smaller and completely round. Furthermore, it was a unique color, it wasn't exactly black but rather a colorless color, an endless hole that carried Kayden's entire path and feelings.
It took him a while to understand that he had to put his way and mind first in advance. That's why his jewel was an abyss, it was just like him and his mind: an endless hole of greed and the desire for power. The new jewel took Kayden's power to another level again. With his constant searches for improvements and increasing the conversion rate, he reached another frightening value during these years.