EXCLUSIVE: After playing the title role in “The Chronicles of Narnia: Prince Caspian,” Ben Barnes is in line for another, as the Brit thesp is in negotiations to star in Warner Bros. and Legendary Pictures’ fantasy tentpole “The Seventh Son.”Legendary had no comment on the casting. Formerly known as “The Spook’s Apprentice,” tale is adapted from Joseph Delaney’s young adult series about a teen who’s the seventh son of a seventh son, and learns about wizardry from a forbidding spook. Jeff Bridges will take on the role of the Spook, while Julianne Moore will play a witch in the pic, which is also slated to star emerging Swedish thesp Alicia Vikander. Sam Claflin (“Snow White and the Huntsman”) had been in negotiations for the title role but those talks fell through. Sergei Bodrov is producing “Seventh Son,” along with Legendary’s Thomas Tull, Thunder Road’s Basil Iwanyk and Lionel Wigram. Jon Jashni and former Legendary exec Alysia Cotter will exec produce, while Legendary’s Jillian Zaks and Thunder Road’s Erica Lee will oversee the project. Barnes recently starred in the indie “Killing Bono” and is currently filming “The Words” with Bradley Cooper. He’s also set to co-star in Justin Zackham’s star-studded wedding comedy “Gently Down the Stream.” Barnes is repped by WME, Luber Roklin Entertainment and by Creative Artists Management overseas.