Danielle Moonstar is one of the fiercest members of the X-Men. She debuted as a member of the original New Mutants, and is known for her role in one of the most striking storylines in Marvel Comics, the "Demon Bear Saga." Originally shown with the ability to create intense psionic visions as well as communicate with animals, Dani has gone on to develop a whole host of other abilities, thanks to her time as a Valkyrie for the Asgardian goddess of death, Hela. But aside from her physical powers, Dani is deeply loyal to her team, never hesitating to provide support to others when they need it most. Mentoring the mutant state's youngest residents along with the other New Mutants, Dani's devotion to helping others has put her in a uniquely perilous situation in Otherworld, covered in New Mutants #16 (written by Vita Ayala, art by Rod Reis, letters by VC's Travis Lanham, design by Tom Muller).
Venturing into Otherworld with Karma (Xi'an Coy Manh) in search of a missing young mutant, the two heroes were imprisoned in the Holy Republic of Fae, a realm notoriously hostile to mutants. Otherworld is a separate dimension best described as a land created from the subconscious of people from the British Isles, embodying elements of Celtic folklore and Arthurian legend. The dimension is unlike reality, allowing for mutants' powers to manifest in unique ways, often reflecting their subconscious.
Dani Moonstar and Karma's entrapment in Otherworld poses a danger for several reasons, namely stemming from the fact that if they were to die there, their resurrections would be corrupted. As was shown in X of Swords, mutants who die in Otherworld cannot be resurrected properly, because of Otherworld's nature as an alternate dimension. This creates makes the resurrection process highly unstable for the Five on Krakoa. When they are resurrected after dying in Otherworld, they return not as the person they once were, but as a completely different version of themselves.
This turn of events for Dani and Karma suggests that a larger force is afoot in Otherworld, one that the X-Men should be concerned about. The manner in which Dani and Karma were captured in the Holy Republic of Fae is suspicious, because of the role that Dani's powers played in their capture. After departing the Kingdom of Avalon with general directions for where the missing mutant Josh went, Dani and Xi'an were trailed by a rabbit. Not keen on searching aimlessly around Otherworld, Dani asked the rabbit if he knew where Josh was, given her ability to communicate with animals. The rabbit appeared friendly, and led them to Fae, where they were immediately captured.
For Dani, her imprisonment in Otherworld possesses a layer of irony, given her history as a Valkyrie. As a Valkyrie, she gained an ability to sense when death was near, and was partly responsible for escorting people to the afterlife after their deaths. Over the years, her powers have fluctuated, but at her most powerful, she was able to kill the god Ares in Dark Avengers/Uncanny X-Men: Exodus #1 (written by Matt Fraction, art by Terry Dodson, Mike Deodato, and Rachel Dodson, colors by Rain Beredo and Christina Strain, letters by VC's Joe Caramagna). With such a powerful mutant like Danielle Moonstar trapped in such an unstable environment, the fate of the X-Men looks dark.