Outlanders(1985)

Showcased for the first time in the U.S. is the book-length short story "The Key of Graciale," starring the alien princess Kahm in an adventure predating her exploits in the now-concluded Outlanders series. Kahm's mission is to retrieve a special magical key from the clutches of an ancient evil wizard. She soon discovers that the key is no mere sorcerer's bauble, but a key to unlock a gate into the dimension of the Dead, a gate that can bring catastrophic consequences to the land of the living - and to Kahm!

(Source: Dark Horse)