Hellfire Butterfly

Hellfire Butterflies are one of three Weekly Boss materials dropped by Signora. This boss is found at the Narukami Island: Tenshukaku Domain in Inazuma City. Reference the image below for its location:

Hellfire Butterflies are awarded by challenging Memories: Duel to the Fiery Death on level II or higher. The recommended party level for this challenge is 70+. If this is one of the first three weekly boss domains you have challenged, collecting the rewards will cost 30 Resin. If you have already completed three weekly boss domains, the cost to collect materials is raised to 60 Resin. You can fight her as many times as you would like, but will only be able to collect materials one time per week. We recommend challenging her at the highest level you can to obtain the most rewards. Weekly Boss rewards reset every Monday at 4:00 AM server time.

A warped shard that houses great might. You obtained this from defeating Signora, who unleashed her original power. The seal of ice was broken under duress, and as her former will surged forth from its pale white prison and she remembered her old name once more, the undying butterfly danced amidst burning flesh and blood. And she remembered her past, wandering the land, spreading the flame, burning away all evil — and she recalled the face of the person she could never meet again.