He’s got game

Gandalf’s got nothing on Ethan Gilsdorf, except for maybe the monster white beard. In his new book, “Fantasy Freaks and Gaming Geeks,’’ Gilsdorf, a teacher at Emerson College and writer whose work also appears occasionally in the Globe, offers an epic quest for reality within a realm of magic. Throw on an invisibility cloak or coat of arms tonight for the discussion, trivia, food, drink (a potion, perhaps?), book signing, and acoustic performance by Harry and the Potters at 8:30. Prizes for trivia winners and those in mystical guise. 7 p.m. Free. Harvard Book Store, 1256 Massachusetts Ave., Cambridge. www.harvard.com