There was little for Vina to do but watch now. She didn't have the skillset to assist Trelumne, and the ritual did not call for her involvement either. With Luna laying down in the circle the druidess kept a safe distance so she wouldn't disturb anything, her azure gaze remaining on her friend with a look that was equally supportive and confident: Trelumne would successfully perform the ritual, so Luna had no reason to be worried.
Once Luna was in position Trelumne closed her eyes and visibly focused, tuning out the world around her as she began to slowly chant. The chant sounded a bit like a song, but a slow and deliberate song, something connected to the ancient world before the time of civilization, when all stories were remembered in song rather than scrolls.
The candles had clearly been made from the Shimmerspot Caps somehow, as indicated by the ghostly blue flames they produced which bathed the entire room in an eerie light. With the entire room closed off it was almost like they were isolated from the rest of the world, and about to enter another world entirely. The green wood they'd gathered appeared to serve multiple purposes: most of it had been placed in the bowls that helped complete the ritual circle, whilst others formed a ring around the whole setup to distinctly divide the inside from the outside. If Vina looked closely she thought she could see how the smoke of the candles never actually left that boundary, but she couldn't be certain due to the lighting and how little smoke there was.
As Trelumne kept chanting her voice began to echo, the strange sounds becoming even stranger until there was the question whether they were truly being formed by an elven tongue. The ghastly light made her visage look otherworldly, which matched her voice in a very disturbing fashion.
Luna had already experienced what it was like to be on the border between the world of the living and the world of the dead, but this was different. That same sensation was there, building up and becoming stronger... but at the same time she felt her own body more acutely than ever. Like she could count every single hair on her skin, feel how her blood flowed through every part of her body. But at the same time this also made her more keenly aware of how her body was not her own: there was something in there mixed with her, the other presence that had turned her into this feline chimaera. This other presence stirred as well, responding to the ritual as it slowly approached its crescendo.
The blue flames from the candles grew longer, reached into the air and towards each other. They wavered in an unseen and unfelt wind, but still reached further and further, fingers of ghostblaze that sought to connect. Trelumne's voice was soft yet filled the room, each syllable echoing inside the ears. There was sweat beading on her forehead and her arms trembled as she held them at her sides. Somebody with sharp eyes would have noticed that her entire body was covered in goosebumps.
There was a brief pause in the chanting, a pause in which the flames froze as well, waiting for what came next.

Drink!
It was the only recognisable word Trelumne had spoken so far, and it was a clear command. There was a strong urgency in her voice, the shaman knowing that if this pause held for too long there could be severe consequences.
The moment Luna emptied the bowl she'd find that, while it tasted awful, it didn't bother her: it wasn't part of her, so just like the rest of the room it felt far away, removed. That is, until it reached her core and spread throughout her body, at which point it felt like snakes of mist were slithering through her body, seeking to escape. The bowls of green wood began to produce mist as well, a low fog that spread across the circle and clung to Luna's skin.
Trelumne frowned as she kept chanting, but her expression became more intense, more focused, more worried. Vina was still confident, but seeing that the elven shaman was clearly not having an easy time did give her some pause. However, there was no opportunity to ask: Trelumne couldn't interrupt her work, and Luna wouldn't understand what was going on. Instead she closed her eyes and hummed softly, so softly that it was barely perceptible. However, that steady rhythm would still reach Trelumne, providing a sense of stability and certainty which helped the elf steel herself as she tackled a complication she'd neglected to take into consideration.
She'd told the two adventurers to retrieve the blood of a living alpha predator, and they'd done exactly as she'd bidden. However, what she hadn't said was that, if possible, the alpha predator wasn't the same as the creature Luna found herself merged with. The lifeblood of the alpha predator combined with the aetheric properties of the Shimmerspot Cap was supposed to serve as a bridge through which the creature could be extracted from Luna's body, but now it was in danger of being dragged straight into the world of the dead.
Raising her trembling arms Trelumne chanted with more force, her expression now firm as the cold flowing through Luna's body finally found its exit, flowing out of her mouth and nose to join the mist produced by the bowls. She could feel the other presence inside of her departing along with it, but... it felt like she herself was also beginning to get pulled along, not her body but the part of her that could feel her body. Something was holding her there, inside of herself, but the pull was growing stronger, and stronger, and stronger...
Right when it felt like she might actually be forced out of her own body a new warmth flowed through her. Or rather, her own being responded to the challenge and answered it with fervour. All the mist flew out of her in one burst, a golden glow enveloping her as both the cold, the strangeness, and the other presence departed, along with all her energy, spent to keep herself whole... if not the same as she was before.
Her feline traits remained, but not as they used to be: the black stripes were gone, and the pure white had been replaced by a beautiful gold, like the sun emerging from the horizon to banish the night. It was clear that the ritual had successfully separated Natiri from her, leaving her one person once more, but it had still left its mark on her.
Meanwhile, the mists from her own body and the bowls had risen up into a swirling clump in the air, right underneath the spot where the ghostly flames met. The blueblaze reached down into the mists and began to burn them away, white nothingness dispering while a condensation of... something... drifted down into the smaller circle opposite of Luna. Like light made liquid it pooled and shimmered, gathering into a vague spherical form which condensed further and further, becoming more defined even as it shrank until it was significantly smaller than a tiger, or even a human.
Instead, once the flames had finished burning away the mists and the shape in the circle had been fully defined, there was a small lion cub curled up in the middle, its fur as golden as Luna's. It was unconscious, but a very subtle movement of its small body indicated that it was breathing, and alive.
And almost without warning the ritual ended: the ghostly flames scattered and died, the light in the room became warm and cozy once more, and the sensation of worlds threatening to collide vanished as if it had never been. The main indicators that the ritual had even happened were the smell, Luna and the cub... and Trelumne, who promptly collapsed, prompting Vina to quickly come over and check if the elven shaman hadn't overexerted herself.

Are you all right?
While she was kneeling next to the panting shaman the question was also thrown at Luna, the vixen trying to pay attention to the both of them at the same time.
@Luna Avalbane