I love this promo. The music is dead on, eerily beautiful; an old child's tale about the rising of Lucifer. It brings to mind the Buffy episode, "Hush". The sneak peek of the return of Alona Tal and the shots of Casitel give us a little something extra to look forward to. Now all we need is a shot of Lucifer himself - the great Mark Pellegrino. September 10th can't come soon enough.
EDIT: Per Watch with Kristin, the song in the promo is called "O Death", sung by Jen Titus and produced special for the show. It should be up on cwtv.com at some point. I'll let you know when.