Nailisi changed her spirit form into a skeleton, and even placed a thread of divine fire into the eye sockets, gradually converting it into soul flame.
She did not need any soul flame for herself. Luoluokaluos were capable of taking different forms, but not taking different souls. She might have taken a spirit form, but she was still a demon. Doing so only enabled her to control attributes of spirits and fight using the methods of the spirits. The very reason Nailisi was converting soul flame was to craft a new Scepter of the Fallen for Nicholas.
She had never tried something like using divine fire before and was doing it completely through her bloodline's instincts. While her soul was capable of absorbing divine fire bereft of a core, it was not the same with the Scepter of the Fallen. Nailisi had to find a stable way to get it done, in order to prevent the old holy master from suffering the recoil brought by the divine fire.
