He knew the spell. He didn't know the how. But then Dracula gets into the how and Jacobi starts to pay attention again.

"Hey, if there was a spell to unpuzzle a code or cypher, then it wouldn't make it fun," he points out, ready to take the notes as he attends, treating this as he did all of his classes in school. With thoughtful care and just a touch of playfulness.

"And yes, I'm aware there's probably a spell for codes and cyphers, but if you have magic do all the work, then what's the point?"