This sounds hell of a lot like Nanto Seiken Shin. He enslaved numerous people to build a grand city for Juria.
 
Except Hope didn’t kill herself, and Twilight didn’t kill Sombra…
 
Nor is Sombra’s symbol a White Cross…
 
Nor do Twilight’s magic blasts cause opponents to explode. (Ignore Too Many Pinkies for the sake of my joke. XD )

@Starswirl  
Radiant Hope is a terrible pony. But don’t ask her writer, he thinks she’s better than Twilight.

@Itsthinking  
same thing

@Itsthinking  
I love how her response to Sombra explaining how he’ll end their prisoners out in the open is “That will be good”.

@OptimusPrimevil  
Nah, show Sombra probably wasn’t a member of some stupid shadow fairy race.

timeline where hope didn’t exist?

Oh yes, he’s totally good inside Hope.