As the last king of humanity, there are many legends about the Flame King.
There are several legends about the Holy Sword, one of which is that the power of the Holy Sword is too strong. To prevent this formidable force from being misused, the Flame King made a contract with the Fire Goddess who gifted her the Holy Sword.
When the Flame King needs power, and her actions align with the contract, she can unseal the Holy Sword and unleash its power by calling out the name of the contract.
No one knows how many layers the seal of the Holy Sword has; some say twelve layers, some say seven, and others say five.
Before the Abyss Watcher became undead, he was also an admirer of the Flame King and knew her series of legends by heart.
Seeing the Flame King call out the name of the contract at this moment, he knew exactly what the Flame King intended to do.
"You won't succeed, I won't let you!"