Wow. Blow me away. There are elements taken from Star Wars - the scene where Luke Skywalker confronts Darth Vader just to see himself, I think it’s a warning from the mysterious intelligence in the Crystal Brighthouse in response to Sunny’s self-reflection about her alicorn powers. And; it’s perhaps the first time I’ve seen Sunny react to books like Twilight’s successor since the movie. The fight scenes between the two alicorns - who are actually not Celestia and Luna even though they came out of the portrait of the royal siblings, but from Sunny’s own subconscious - good versus evil. Which seems to be a copy of a fantastic fan work of the fight between Nightmare Moon and Celestia from so long ago. Sunny was deeply shaken, but she had learned that with great power comes its risks.
Now I’m definitely sure that the mysterious intelligence can only be Twilight Sparkle who projected her actions from afar because only an alicorn would be able to create the episode where Sunny is confronted with the dark side of the alicornhood. Twilight perhaps more than anything knows how easily power can corrupt, and that one needs to be a good alicorn in awareness of the risks. It could mean that something might be wrong with Skyros, maybe there is a friendship problem there between the alicorns who had failed to help when Opaline attacked Equestria.
Misty as usual is the balancer of the group, she helped Sunny out and made her comfortable with the fact of her inner struggles.
As we all know, all alicorns carry within them a potential for evil that can erupt because they are among the most powerful beings in the entire world. Nightmare Moon. Daybreaker. Midnight Sparkle. Opaline.
The new issue about Cadence showed that a full-grown alicorn at full strength can fight an army of dragons, and Sunny had trouble with a very unusually strong dragon with supernatural powers. That said, Sunny was not as strong as an alicorn, when Opaline was at her full strength it was very lucky that she didn’t go all-out.
So if the Rainbow of Light locket is in Sunny’s possession, she should take it with her to Skyros. It will give her an advantage even against hordes of hostile alicorns.