Matthew K. Manning 
Search for Stalor [PDF ebook] 

Xander Stone must save the handsomest of all Rainbow-Barfing Unicorns! In this instalment, the handsomest of all Rainbow-Barfing Unicorns, Stalor, is missing. (P.S. He’s not really that handsome.) Twelve-year-old Xander and his other stinky, zombielike, upchucking unicorns set out to find him. Their naively heroic quest leads them to another dimension ruled by a diabolically bizarre king. Can the Rainbow-Barfing Unicorns save their relatively handsome friend, or will the plan throw up in their faces?