This is Star Singer, an important supporting character in ASGeek2012’s story: https://www.fimfiction.net/story/359176/pandemic
 
Without spoiling anything too major, she is Moon Dancer’s aunt and a friend of Sunset Shimmer. Her special talent is being able to “sing” to the stars and see possible future threats to Equestria.
 
She goes into this trance-like dream state where she does this weird “singing” thing (I’d have to check the text of the story for details I’ve forgotten), and she can sort of see future threats.  
And it’s these visions of a possible future which kickstart Sunset Shimmer’s decades-long plan to save Equestria, which leads to the events of “Pandemic”.  
But Star Singer is horrified at what Sunset Shimmer ended up doing (turning all of humanity, had Twilight not interfered, into ponies). And the threats she foresaw in her vision almost came to past, but were stopped by Twilight and her friends after Sunset had gone to the human world. (This is a very different Sunset Shimmer than the canon one.)