She did indeed render the greatest power unto utter desolation.
I think that phrase gets the grammar wrong. "Render unto" means to give to: "Render unto Caesar what is Caesar's" means "give the Romans what they're entitled to." Rearrange that and you get "Render [what is Caesar's] unto Caesar." So "render A unto B" means "give A to B." How do you give the greatest power to utter desolation? I think the writers intended it to mean that she would use the greatest power to cause utter desolation, but "render... unto" is decidedly not the correct construction to use for that. They were just trying to sound all fancy and archaic and didn't think it through.