For a demon to transform their Flickering Heart to a Burning Heart, what the demon had to do was simple and at the same time... extremely dangerous.
Burn their heart using their Chaos Flame.
Despite the fact that a demon's heart was the vessel of a demon's chaos flame, the chaos flame could still damage a demon's heart... especially during an advancement to a higher rank.
Simon's eyes were closed as he could feel and see his dark silver chaos flame in his demon heart.
With an extremely focused expression and his mind tuning out every single thing, he controlled his chaos flame which was at the center of his demon heart to flow to the right part of his demon heart.
When it came to a demon's chaos flame, one could say that it was inside a demon's heart and at the same time, it was not.
For those with sharp senses, they'd realize that the chaos flame was actually in another space. It was actually not in their heart, but at the same time, it was.
