Stick Time: Scariest Piece?

In trying to find a little something spooky for Halloween, I occurred that scariest piece of music I ever conducted (on a Halloween, oddly enough) was the Thomas Tallis “Spem in Alium,” a monolithic 40-voice “motet” scored for eight choirs of five voices each set in a score that stands two feet tall.  Don’t misunderstand . . . I adore the Renaissance and it’s a beautiful work, but trying to keep a choir of 19-year olds moving forward on a 40-voice work is not for the faint of heart.