In the Arora World, after his battle against the Shadow Bat, Evan had accidentally fell into the ruin of the Shadow Kingdom dungeon.
That ruin was completely different from any other ruin he had ever seen. There was no monster in that ruin nor there was any reward in it. When he was about to die there, he heard a cold emotionless voice, which was neither male nor female asking him what he wanted to sacrifice.
At that time, out of anger because of his Shadow Physique which did not allow him to absorb any core other than the shadow core, Evan had sacrificed his shadow physique and awakened his Shadow Monarch Physique.
Although it has been over a year, Evan still hasn't forgotten the voice he heard in the Shadow Kingdom dungeon... and the voice of the spirit of the Tower of Ascension was very similar to that voice. In fact, calling it similar would be an understatement because its voice was exactly like that voice.