Trying to Invade the Dungeon

There were various rituals that Asura had taught William. Most of them worked by transferring demonic energy from William's body—and what Asura had stored in the sword—to the user, in this case, Victoria.

But for it to work, a kind of sacrifice was necessary. The idea was to take the life force of creatures, absorb it, and use it as a conduit for the demonic energy.

This way, William could use the life force of the slain creature for himself, maintaining his strength.

If he simply passed his demonic energy or the energy from the sword to Victoria, it would eventually run out.

Not to mention, he would feel weaker. However, by using the life force of slain creatures and the magical symbols of the ritual, it was possible to mitigate this negative effect.

And it could go even further. There was another ritual that could send demonic energy to William if Victoria performed a sacrifice for him.