Man, this is tough, but I went with the return of the Dark Lord with Season 1 turned upside down. It reminds me a lot of the “World of Ruin” in the post-apocalyptic era of Final Fantasy III SNES, which I think is now Final Fantasy VI for Playstation? Maybe they can add a scene at an opera house involving Elena.
Edit: I do understand that OP was from early last year and Season 3 starts Thursday, but you never can start too early wondering about the next chapter in the story to follow.