Wild theory:

Spoiler: Whispers
Show
The Dweller in Darkness works by lurking in another dimension and getting in the heads of mystically attuned folks to make them think they hear their lost loved ones, creating an obsession in their minds. This attracts them to try and bore through the barrier separating our world from its, inadvertently freeing it.

...Isn't there another Marvel character besides Wen Wu currently hearing her loved ones desperately needing her, in her head?