Seanna

Seanna is a slinky mage dwelling in Buccaneer's Den during Ultima IV.

Description
Seanna could be found in a grove on the southwestern corner of the isle. Should the Stranger ask about her occupation, Seanna told the hero she was a sorceress, and asked if she could help the hero with anything... perhaps magic. Seanna suggested, in her soothing, hypnotic voice, that instead of using the incorrect formula given for the Sleep spell in the  Book of Mystic Wisdom which calls for a double portion of spider's silk, the hero try using only a single portion of the reagent. She seemed, throughout the entirety of the conversation, to have a fixation on repeating the word "sleep" in a lilting repetitive chant... almost as if it she were trying to lull the hero into unconsciousness.

Trivia

 * Cosima of Moonglow offers similar advice regarding the Sleep spell, which had had its formula misprinted in the Book of Mystic Wisdom