I DON'T KNOW how you blow it when your movie includes Julianne Moore playing a witch who can turn into a dragon, but the makers of Seventh Son have managed it.
Based on British author Joseph Delaney's book The Spook's Apprentice—renamed The Last Apprentice: Revenge of the Witch in the US, presumably because of problems with the word "spook"—Seventh Son is a dimwitted fantasy about an apprentice, and a witch, and this thing called a spook, which is sort of like a Van Helsing, or maybe a Grimm? His job is to kill a bunch of monsters, except for the good ones (Julianne Moore's witch is not one of the good ones). The spook is played by Jeff Bridges, using a marble-mouthed, gravel-coated but sing-songy voice that even Adam Sandler would have realized was a bad idea.
But the real problem is the apprentice, played by a piece of soggy cardboard named Ben Barnes. He's totally devoid of personality—on his character sheet, I bet you'd find his Charisma and Wisdom scores locked firmly down at 3, with Intelligence at maybe a 4. His apprenticeship is boiled down to a couple of brief CGI encounters with some not particularly fearsome monsters. There's a love interest who's also a witch, and a gentle and kind mother who's also a witch—actually, come to think of it, every female character in Seventh Son turns out to be some kind of witch. The screenplay throws in a bunch of prophecies, and a magic stone, and a friendly sort of ogre fellow named Tusk (John DeSantis) who I think is supposed to be comic relief.
All this should be a lot more fun than it is, but Seventh Son just sort of lies there, lifeless and inert. The final showdown is handled embarrassedly, as if the filmmakers were like, "Okay, we've got to end this fiasco, quick." Even the lamest D&D campaign you've ever played has a better storyline. On a scale of 1d20, Seventh Son rolls a one, and that's being generous.