David Auburn is looking for witches and vampires and has come on to adapt Deborah Harkness’ “A Discovery of Witches” for Warner Bros. and producers Denise Di Novi and Allison Greenspan.Studio acquired the property last summer. Story centers on a reluctant witch and a 1,500-year-old vampire. The witch — a direct descendant of the first woman executed in the Salem Witch trials — accidentally unlocks an enchanted manuscript and finds herself in a race to prevent an interspecies war. Auburn’s best known as the author of the play “Proof,” which won the 2001 Tony Award for Best Play and the 2001 Pulitzer Prize for drama. He subsequently adapted the play for the 2005 film. Auburn also wrote the script the 2006 feature “The Lake House.” Warner-based Di Novi is a producer on Steve Carell comedy “Crazy Stupid Love” and has produced a quartet of Nicholas Sparks film adaptations — “Message in a Bottle,” “A Walk to Remember,” “Nights in Rodanthe” and upcoming “The Lucky One,” starring Zac Efron. Auburn is repped by CAA.