Okay, I get it now. I absolutely see why people are saying to read this one first. There are quite a lot of plot points and backstories mentioned that could be beneficial to TWOTQ.

✔️More details about Primal and the hierarchy in Illesium.
✔️The prophecy
✔️Intros for characters we'll get more of later.
✔️Draken!
✔️Revenants! (I kind of forgot about those guys) 

Now, the first half of this book was truly useless to me. I kind of hated it actually. I was not truly interested until the events that lead to Sera getting to the Shadowlands. Everything afterwards was 👌🏻.

Are they just Poppy and Cas in a different font? Yeah. But I love Poppy and Cas so I am actually really interested in Seraphina and Nykyos's relationship and continuing story.