Unicorn Boy and the Slumber of Doom Graphic Novel

Brian always felt a bit different compared to other kids. Even before growing a unicorn horn, discovering a talking muffin and swallowing the ruler of the Underworld to save his BFF. So when he receives a mysterious invitation for a Unicorn-Only Sleepover, Brian wonders if these fellow magical creatures might help him make sense of his increasingly odd world!
But held in an enchanted castle in the clouds, not everything at this glitzy, glamorous party is as it seems . . .
Are the negative feelings in his gut just anxiety, or is something else at play?