Please hide WN/LN/manga spoilers.
MAL entry, Anilist. The zeroth episode is a spin-off-ish, focusing on Sylphy after the Calamity meeting with Ariel, becoming “silent Fitz”, and struggling with her new situation; as well as the power struggles between Ariel and her brother I-always-forget-his-name for the Asuran throne.
I mean yeah, it’s not like I was a fan of it then either. I don’t think it’s entirely fair to say it’s a core part of the show like card games are to yugioh either. The show does not revolve around being creepy. Particularly in this episode, it’s not like it’s preceded or followed by anything that makes it connected to the world or plot building.