Capítulo 757: The Fairies' Dimensional Pocket.

"Since you ended up increasing your poison affinity without my help, I will give you a treasure that is desired by the Fairy Matriarch." Lady Sphinx suddenly offered.

"Much appreciated!" Felix said with an ecstatic tone.

"Don't thank me, it's what I promised you before." 

When Felix won the last game and earned two monoliths for Lady Sphinx, he was asked for a request as a show of gratitude.

Felix requested her help to improve his elemental capacity, but he was shown the conversion technique.

She promised that she would help him with increasing his affinity at least, but Felix's speed turned out to be not that bad.

So, she decided to cash out his request with this matter.

Felix was beyond happy about it. He knew that If you brought a treasure that was desired by the Fairy Matriarch, she would personally handle fairy dust ritual.