Morpheus

The "Morpheus" is a magical book of dreams that plays a key role in several titles in the Elsaverse saga. Originating from the parallel world, it contains different spells that let its readers interact with people's dreams, as long as those readers have roots in the parallel world themselves.

A copy of the book got to Sangrive's realm a few centuries ago, when a Dream Master named Troi was trying to run away from Xara after violating their King Morland's dreams. Realizing there was no possible escape from his chaser, Troi decided to give the book away to Mary, the woman who helped him in this realm. Although that original version was written in the parallel universe's main language, Mary was able to read it as, during their brief encounter, Troi had also taught her that language in a shared dream. It's unknown whether Troi's was the only copy that ever traveled from one realm to the other, as well as whether Mary was the only human to understand that language, but at some point in history the "Morpheus" got translated and several copies of it were printed in English.

Apparently, and according to Elsa's research in Dreaming with Elsa (2015), many nasty incidents involving the book occurred throughout the following decades, with people entering others' dreams to abuse and hurt them. For that reason, most of those copies ended up burnt or destroyed: although there are still a few minor, incomplete fragments around, the one Elsa's family owns since many generations ago seems to be the only intact copy still existing in Sangrive's realm. Due to those negative incidents from the past, the admonishing of never opening the book had passed from father to son for several generations until Elsa finally broke that rule when Chloe Reyes tried to steal the book from her in the saga's foundational title.

Despite this "Morpheus" copy being translated, though, the knowledge contained in the book isn't available for ordinary humans: even though everyone could read the words on it, only those whose ancestors were from the parallel universe can actually get its meaning and cast the magic spells described in the "Morpheus". As it's explained in the short story DwE: Multiplicity (2017), at first glance the book just doesn't make any sense, and it's only after reading and learning different spells when other parts of it can be accessed and become actually understandable. Every spell is written after an introductory text that tells how a Dream Master made use of it at some point in history; although Elsa thinks those are just fictional stories, those events might actually have taken place in the parallel world.

The book is a highly valuable artifact for those who know about its existence and could perform the powerful dreaming spells it contains. Morland Reyes tried to get it but failed as his daughter Chloe was caught by Elsa using the weak dream-linking spell contained in the only fragment Morland was able to find, but his son Charles eventually managed to steal the book from Elsa's safe in the short story Elsaverse: Transitions (2020-2021), with Trisha Blackhawk as the actual perpetrator.