I Became a Dark Fantasy Villain

As Ian expected, the ring was the key that controlled every incantation and spell circuit of the magic tower.

Swoosh—

Even now, Ian could clearly see the pure white Mantra circuits carved inside the ring slowly losing their light, which was precisely why he had taken notice of it from the beginning.

"I figured it had some role like that," said Thesaya, wiping the blood from her nose with the back of her hand.

Then she glanced upward. "But why are the spell circuits still like that?"

Ian turned to her as she finally approached. "I haven’t put it on yet."

"Ah, right," Thesaya stopped where she stood.

She gave him a slight smile. "Well, since you’ve already taken the most valuable thing… would you mind if I kept that staff?"

So that was what she was getting at.