Lilith's plan was nothing short of brilliant. Her allies would not realize what she'd done, her off-again on-again enemies would not realize what she'd done. All the evidence would lead straight back to those she wanted to.
Sadly, Circe had one slight, but fatal mistake. She'd only ordered the demon to dispose of Vixi's body.
Circe's wards she'd set up around the amusement park still under construction weren't attuned to sense demon kind, she didn't want the alarm to go off every time Rexi visited after all. So the demon entered without problem.
And Vixi and her fellow, would magically enhanced by Circe in many areas, were still flesh and blood creatures, so it was only a matter of time before Vixi asked to go to the little fox's room... And not having any rational reason to expect an assassin, she'd been allowed to go alone.
Not wanting to draw attention of make victims wonder, the shadow demon had chosen to be swift and efficient rather than draw out the anthro's suffering as it would have preferred.
Vixi had done her business, walked to the skink to wash her hands, and had looked at her reflection, confused when she saw her eyes glowing red. Then the reflection's arms reached out and grabbed her neck. The reflection's unholy strength broke her neck instantly. Vixi was dead before she would've hit the floor. But instead the hands held her, and pulled the dead body inside the mirror, and the shadow demon in Vixi's form a few minutes later stepped out, having read Vixi's brain for the inform it needed to put up this farce and what was expected of it to act as Vixi's servant.
"I am sorry my goddess for my delay, I am ready to continue," the shadow demon said as she stepped back into Circe's office, a perfect imitation of Vixi's voice, grammar, tone, and body language. The shadow demon would've been a poor spy if it couldn't impersonate it's targets in every possible physical way.
There was no response. Everyone in the room was looking at her, everyone. Include the transparent small humanoid fox woman in the palm of Circe's hands. Vixi had sworn her soul to Circe by default, like devote follower of a deity. Lilith's plan had been brilliant. She had made one slight oversight. She hadn't ordered the demon to take care of Vixi's soul first... and she'd thought that the devotion Circe's new follows shows her were just words with no impact on anything.
"OH SHI-" the demon had time to get out before a blast from every magic user in the room struct it at once.
When the shadow demon came to... it realized it was still in the flesh and blood form of Vixi, well, what was left, it's head was... sealed in a glass sphere. It shouldn't have been able to speak, lacking a throat and lungs and diaphragm, but it was able to provide the force and sound to speak anyway.
"Oh shit."
Baga Yaga, Circe, the two humans, and Vixi's soul, clinging to her goddess, looked down at the imposter's glass bubble encased head.