Blightwraith

They are found in the Ghostlands, homeworld of the undead, they would often lead hordes of specters there.

Blessed with human intelligence from the very start, they're called as Noble Ghosts by many. They require the power called Blight, created by one of the Primordials, Blightfather himself.

The Blightfather turned Casper's girlfriend Lyra into one after Jake completing the Tutorial. Since she is sealed in Casper's necklace, she rarely comes out to show her abilities, often communicating via telepathy with Casper which could be due to her being bonded to Casper, similarly how Sylphie's emotions could be discerned by Jake due to the bond.